Low-Carb vs. Low-Fat – Time to Retire The Fad

A picture of Low Carb Vs Low FatLow-carbohydrate diets have a long history of therapeutic use for obesity, diabetes and epilepsy.

Millions of people all around the world have tried such a diet, usually with good results.

Despite that, nutritionists and health authorities do not recommend such a diet and in fact claim that it is dangerous.

They claim that low-carb diets don’t have scientific evidence behind them and often refer to them as “fad diets.”

With this article, I plan to prove them wrong.

It is true that 10 years ago low-carbohydrate diets didn’t have any major scientific evidence behind them.

But since the year 2003, at least 21 randomized controlled trials have been performed on humans.

Ask anyone with a background in nutrition, public health and medical science, and they will tell you that randomized controlled trials are the gold standard to prove safety, cause and effect.

Here I will review each one of those 21 trials. All of these are published in respected, peer-reviewed research journals such as the New England Journal of Medicine, American Journal of Clinical Nutrition and Nature.

There was no cherry picking of data here.

I have specifically asked nutritionists that are against the use of low-carb diets to find me controlled trials that demonstrate that they are either ineffective or unsafe, but the fact is that such trials do not exist.

All the studies are randomized controlled trials comparing a low-carb diet to the standard calorie restricted low-fat diet that is generally recommended by health professionals.

I do not believe that any one diet plan is perfect for everyone. The best diet plan is the one that an individual can follow in the long term to make it a permanent lifestyle change.

However, I want the media, the public as well as professionals to acknowledge low-carb diets as a viable option for those with obesity or other symptoms of the metabolic syndrome (which are the biggest health problems in the world).

People should be given the choice, especially when all the scientific evidence suggests that low-carb is easier, healthier and more effective than the calorie restricted, low-fat diet that is generally recommended, despite overwhelming contrary evidence.


1. A randomized trial of a low-carbohydrate diet for obesity.
Gary D. Foster, Ph.D., Holly R. Wyatt, M.D., James O. Hill, Ph.D., Brian G. McGuckin, Ed.M., Carrie Brill, B.S., B. Selma Mohammed, M.D., Ph.D., Philippe O. Szapary, M.D., Daniel J. Rader, M.D., Joel S. Edman, D.Sc., and Samuel Klein, M.D. – N Engl J Med 2003; 348:2082-2090

Details: 63 obese men and women, randomly assigned to either a low-carb, high fat Atkins diet or a conventional low-fat diet. Low-fat group is calorie restricted. Outcomes measured are weight loss and cardiac risk factors.

Weight Loss: Greater on the low-carb diet at 3 months (-6.8% vs. –2.7%) and 6 months (–7.0% vs. –3.2%). Difference not statistically significant at 12 months (–4.4% vs. –2.5%).

Cardiac Risk Factors: Increase in HDL and decrease in Triglycerides on low-carb diet. Also an increase in Total and LDL cholesterol at 3 months, compared to the low-fat diet, but not statistically significant at 6 and 12 months.

2. A Low-Carbohydrate as Compared with a Low-Fat Diet in Severe Obesity
Frederick F. Samaha, M.D., Nayyar Iqbal, M.D., Prakash Seshadri, M.D., Kathryn L. Chicano, C.R.N.P., Denise A. Daily, R.D., Joyce McGrory, C.R.N.P., Terrence Williams, B.S., Monica Williams, B.S., Edward J. Gracely, Ph.D., and Linda Stern, M.D. – N Engl J Med 2003; 348:2074-2081

Details: 132 severely obese subjects with a mean body mass index of 43. High prevalence of diabetes (39%) and the metabolic syndrome (43%). Assigned to a low-carb diet or a low-fat, calorie restricted diet.

Weight Loss: Greater weight loss on the low-carbohydrate diet at 2, 4 and 6 months. Weight loss at 6 months was -5.8kg on the low-carb diet vs. -1.9kg on the low-fat diet.

Risk Factors: Greater improvements on the low-carb diet for triglycerides, insulin sensitivity, blood glucose levels. Insulin levels in non-diabetic subjects improved on a low-carb diet. Results for HDL, LDL and Total Cholesterol were not statistically significant.

3. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents
Stephen B. Sondike, MD, Nancy Copperman, MS, RD, Marc S. Jacobson, MD – J Pediatr 2003;142:253-8

Details: 30 overweight adolescents randomized to either a low-carb or a low-fat diet for 12 weeks. Neither group is calorie restricted.

Weight Loss: The low-carb group lost an average of 9.9kg, while the low-fat group lost 4.1kg.

Risk Factors: Greater improvements on the low-carb diet for triglycerides and non-hdl cholesterol. Greater improvements in Total and LDL cholesterol in the low-fat group. No statistically significant results for HDL cholesterol.

4. A Randomized Trial Comparing a Very Low Carbohydrate Diet and a Calorie-Restricted Low Fat Diet on Body Weight and Cardiovascular Risk Factors in Healthy Women
Bonnie J. Brehm, Randy J. Seeley, Stephen R. Danials, and David A. D’Alessio – The Journal of Clinical Endocrinology & Metabolism April 1, 2003 vol. 88 no. 4 1617-1623

Details: 53 obese women randomized to two groups: a low-carb diet group and a low-fat diet group, for 6 months. Low-fat group is calorie restricted.

Weight Loss: The low-carb group lost more weight (8.5kg) compared to the low-fat group (3.9kg) at 6 months.

Risk Factors: At 6 months, both groups had increased HDL cholesterol. Triglycerides decreased substantially in the low-carb group, but remained the same in the low-fat group. LDL and total cholesterol didn’t change much in either group at 6 months.


5. The National Cholesterol Education Program Diet vs a Diet Lower in Carbohydrates and Higher in Protein and Monounsaturated Fat
Y. Wady Aude, MD; Arthur S. Agatston, MD; Francisco Lopez-Jimenez, MD, MSc; Eric H. Lieberman, MD; , MS, RD; Melinda Hansen, ARNP; Gerardo Rojas, MD; Gervasio A. Lamas, MD; Charles H. Hennekens, MD, DrPH – Arch Intern Med. 2004;164(19):2141-2146.

Details: 60 participants were randomized to either a modified low-carb diet or a low-fat diet based on the National Cholesterol Education Program. Both groups are calorie restricted.

Weight Loss: The modified low-carb group lost an average of 13.6lb (6.2kg) while the low-fat group lost an average of 6.1lb (2.8kg).

Cardiac Risk Factors: There were no significant differences in blood lipids between groups. The modified low-carb group decreased total cholesterol, triglycerides, and percentage of dense LDL while increasing LDL particle size. The low-fat group decreased total, HDL and LDL cholesterol.

6. A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia: A Randomized, Controlled Trial
William S. Yancy Jr., MD, MHS; Maren K. Olsen, PhD; John R. Guyton, MD; Ronna P. Bakst, RD; and Eric C. Westman, MD, MHS – Ann Intern Med. 18 May 2004;140(10):769-777

Details: 119 obese and hyperlipidemic individuals randomized to either a low-carb, ketogenic diet or a low-fat diet. Low-fat group was calorie restricted.

Weight Loss: Group on the low-carb diet lost an average of 12.0kg, while the low-fat group lost an average of 6.5kg.

Risk Factors: Triglycerides decreased and HDL cholesterol increased on the low-carb diet. Total cholesterol and triglycerides decreased on the low-fat diet. There was a significant difference between groups for triglycerides and HDL, in favour of the low-carb diet.

7. Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women
JS Volek, MJ Sharman, AL Gómez, DA Judelson, MR Rubin, G Watson, B Sokmen, R Silvestre, DN French and WJ Kraemer – Nutrition & Metabolism 2004, 1:13

Details: 28 overweight/obese men and women are randomized to either a calorie restricted low-carb diet or a calorie restricted low-fat diet. The low-carb group ends up eating about 300 calories more per day. Outcomes measured are weight loss, body composition, trunk fat mass and resting energy expenditure.

Weight Loss: The low-carb group lost more weight than the low-fat group, despite eating more calories. The men lost more weight than the women. The ratio of trunk fat/total fat also decreased during the low-carb diet (trunk fat, or abdominal fat, is the worst).

Other outcomes measured: Resting energy expenditure did not decrease on the low-carb diet, but it did decrease on the low-fat diet. The loss of fat in the trunk region was three times greater on the low-carb compared to the low-fat diet.

8. Comparison of a Low-Fat Diet to a Low-Carbohydrate Diet on Weight Loss, Body Composition, and Risk Factors for Diabetes and Cardiovascular Disease in Free-Living, Overweight Men and Women
Kelly A. Meckling, Caitriona O’Sullivan, and Dayna Saari – J Clin Endocrinol Metab. 2004 Jun;89(6):2717-23.

Details: 40 overweight and obese men and women randomized to either a low-carb or a low-fat diet. The calories in the low-fat group were matched to the calories in the LC group, although the LF group eventually ate a bit less. Study went on for 10 weeks.

Weight Loss: Both groups lost a similar amount of weight. LC lost 7.0kg and the LF group lost 6.8kg. No statistically significant difference.

Risk Factors: Total and LDL cholesterol remained unchanged in the LC group but decreased in the LF group. HDL decreased in the LF group and increased in the LC group. Both groups lowered their triglyceride levels.


9. Perceived Hunger Is Lower and Weight Loss Is Greater in Overweight Premenopausal Women Consuming a Low-Carbohydrate/High-Protein vs High-Carbohydrate/Low-Fat Diet
Sharon M. Nickols-Richardson, PhD, RD; Mary Dean Coleman, PhD, RD; Joanne J. Volpe; Kathy W. Hosig, PhD, MPH, RD – J Am Diet Assoc. 2005;105:1433-1437

Details: 28 overweight/obese premenopausal women were placed on either a low-carb/high-protein or a high-carb/low-fat diet for 6 weeks. Primary outcomes measured were hunger and cognitive eating restraint. High-carb/low-fat group was calorie restricted.

Weight Loss: The women on the low-carb/high protein diet lost more weight (5.7% of body weight) compared to the high-carb/low-fat group (3.3% of body weight).

Outcomes Measured: The LC/HF group of women had less hunger than the HC/LF group, but both groups exhibited similar cognitive eating restraint (CER).

10. Short-term effects of severe dietary carbohydrate restriction advice in Type 2 diabetes — a randomized controlled trial
M. E. Daly, R. Paisey, R. Paisey, B. A. Millward, C. Eccles, K. Williams, S. Hammersley, K. M. MacLeod and T. J. Gale – Diabet. Med. 23, 15–20 (2006)

Details: 102 type II diabetics randomized to either a low-carb or a low-fat diet. Study went on for three months. Main outcomes measured were weight, glycaemic control, lipids and blood pressure. The low-fat group was instructed to reduce portion sizes.

Weight Loss: The LC group lost more weight, -3.55kg, while the LF group lost 0.92kg.

Other Outcomes Measured: The ratio of Total cholesterol:HDL improved on the LC group. Triglycerides, Systolic blood pressure and HbA1c (a marker for blood glucose levels) also decreased on the LC diet, but the difference was not statistically significant compared to the low-fat diet.


11. The Effects of a Low-Carbohydrate Ketogenic Diet and a Low-Fat Diet on Mood, Hunger, and Other Self-Reported Symptoms
F. Joseph McClernon, William S. Yancy Jr., Jacqueline A. Eberstein, Robert C. Atkins and Eric C. Westman – Obesity. 2007; 15:182–187.

Details: 119 overweight individuals randomized to either a low-carb, ketogenic diet or a calorie restricted low-fat diet for 6 months. Main outcomes measured are mood, hunger and other self reported symptoms.

Weight Loss: The LC group lost 12.9kg, while the LF group lost 6.7kg.

Other Outcomes Measured: The LC group had significantly better mood (less negative affect) and less hunger than the LF group.

12. Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women – The A TO Z Weight Loss Study: A Randomized Trial
Christopher D. Gardner, PhD; Alexandre Kiazand, MD; Sofiya Alhassan, PhD; Soowon Kim, PhD; Randall S. Stafford, MD, PhD; Raymond R. Balise, PhD; Helena C. Kraemer, PhD; Abby C. King, PhD – JAMA. 2007;297(9):969-977

Details: 311 overweight/obese premenopausal women assigned to either an Atkins, Zone, LEARN or Ornish diet for 12 months. Zone and LEARN were calorie restricted, Atkins and Ornish were not.

Weight Loss: Weight loss was greatest at 12 months in the Atkins group (-4.7Kg) compared to the LEARN (-2.6Kg), Zone (-1.6Kg) and Ornish group (-2.2kg).

Risk Factors: Triglycerides decreased and HDL increased on the Atkins diet. LDL cholesterol favoured the LEARN and Ornish (low-fat) groups at 2 months, but the effects dimished at 6 and 12 months. Systolic blood pressure was significantly lower in the Atkins group at 12 months compared to the other groups, and diastolic blood pressure significantly lower than the Ornish (very low fat) group.

13. Low- and high-carbohydrate weight-loss diets have similar effects on mood but not cognitive performance
Angela K Halyburton, Grant D Brinkworth, Carlene J Wilson, Manny Noakes, Jonathan D Buckley, Jennifer B Keogh, and Peter M Clifton – Am J Clin Nutr 2007;86:580 –7.

Details: A low-carb diet compared to a low-fat diet in 93 overweight or obese individuals for 8 weeks. Outcomes measured were weight loss, mood and cognitive function. Both groups were calorie restricted.

Weight Loss: The LC group lost more weight, 7.8kg, compared to the LF group which lost 6.4kg.

Other Outcomes: Both LC and LF groups had significant improvements in mood, with no difference between groups. Both groups improved cognitive function. Speed of processing improved less in the LC group.

14. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects.
P. A. Dyson, S. Beatty and D. R. Matthews – Diabet. Med. 24, 1430–1435 (2007)

Details: 13 diabetic and 13 non-diabetic individuals randomized to either a low-carb or a low-fat diet for 3 months. Main outcomes measured are body weight, glycated hemoglobin (HbA1c), ketone and lipid levels. Low-fat group was calorie restricted.

Weight Loss: The LC group lost 6.9kg while the low-fat group lost 2.1kg.

Other Outcomes Measured: There was no statistically significant difference in any of the other parameters.


15. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet.
Iris Shai, R.D., Ph.D., Dan Schwarzfuchs, M.D., Yaakov Henkin, M.D., Danit R. Shahar, R.D., Ph.D., Shula Witkow, R.D., M.P.H., Ilana Greenberg, R.D., M.P.H., Rachel Golan, R.D., M.P.H., Drora Fraser, Ph.D., Arkady Bolotin, Ph.D., Hilel Vardi, M.Sc., Osnat Tangi-Rozental, B.A., Rachel Zuk-Ramot, R.N., Benjamin Sarusi, M.Sc., Dov Brickner, M.D., Ziva Schwartz, M.D., Einat Sheiner, M.D., Rachel Marko, M.Sc., Esther Katorza, M.Sc., Joachim Thiery, M.D., Georg Martin Fiedler, M.D., Matthias Blüher, M.D., Michael Stumvoll, M.D., and Meir J. Stampfer, M.D., Dr.P.H. for the Dietary Intervention Randomized Controlled Trial (DIRECT) Group – N Engl J Med 2008; 359:229-241

Details: 322 moderately obese individuals randomized to either a low-fat calorie restricted diet, a mediterranean calorie restricted diet or a low-carb non-restricted diet for 2 years.

Weight Loss: The LF group lost 2.9kg, the mediterranean group lost 4.4kg and the LC group lost 4.7kg.

Risk Factors: The LC group improved both HDL and Triglycerides, and the ratio of Total:HDL cholesterol, compared to the other groups.

16. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus
Eric C Westman, William S Yancy Jr, John C Mavropoulos, Megan Marquart and Jennifer R McDuffie – Nutrition & Metabolism 2008, 5:36

Details: 84 obese and type II diabetic individuals randomized to either a low-carb ketogenic diet or a low glycemic index calorie-restricted diet for 3 months.

Weight Loss: The LC group lost 11.1kg and the LF group lost 6.9kg.

Other Outcomes Measured: The LC group had more improvements in HbA1c and High-Density Lipoprotein. Diabetes medication were reduced or eliminated in 95.2% of the LC group, compared with 62% of the low glycemic index diet.

17. Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity
Jennifer B Keogh, Grant D Brinkworth, Manny Noakes, Damien P Belobrajdic, Jonathan D Buckley, and Peter M Clifton – Am J Clin Nutr 2008;87:567–76.

Details: 107 individuals randomized to either a very low-carbohydrate diet or a low-fat diet for 8 weeks. Both groups were calorie restricted. Main outcomes measured were markers of endothelial function and cardiovascular disease risk.

Weight Loss: The LC group lost more weight, 7.5kg, compared to the LF group which lost an average of 6.2kg.

Risk Factors: There was no difference between groups on endothelial function. The LC group had further improvements in Triglycerides and HDL, compared to the low-fat group.

18. Metabolic Effects of Weight Loss on a Very-Low-Carbohydrate Diet Compared With an Isocaloric High-Carbohydrate Diet in Abdominally Obese Subjects
Jeannie Tay, BNUTRDIET (HONS), Grant D. Brinkworth, PHD, Manny Noakes, PHD, Jennifer Keogh, MSC, Peter M. Clifton, PHD – J Am Coll Cardiol 2008;51:59–67

Details: 88 obese individuals randomized to either a low-carb, high-fat diet or a high-carb, low-fat diet for 6 months. Both groups were calorie restricted. Main outcomes measured were weight loss and cardiac risk factors.

Weight Loss: The LC group lost 11.9kg and the LF group lost 10.1kg. The difference between groups was not statistically significant.

Cardiac Risk Factors: Triglycerides and HDL improved further in the LC group, while Total and LDL cholesterol improved in the LF group. 24% of individuals on the low-carb diet increased LDL cholesterol by 10% or more.


19. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet.
Jeff S. Volek, Stephen D. Phinney, Cassandra E. Forsythe, Erin E. Quann, Richard J. Wood, Michael J. Puglisi, William J. Kraemer, Doug M. Bibus, Maria Luz Fernandez, Richard D. Feinman – Lipids, 2009, Volume 44, Number 4, Pages 297-309

Details: 40 subjects with atherogenic dyslipidemia randomized to either a low-carb or an isocaloric low-fat diet for 12 weeks. Main outcomes measured were markers of the metabolic syndrome.

Weight Loss: Despite a similar reduction in calories, the low-carb group lost double the amount of weight as the low-fat group (10.1kg vs. 5.2kg).

Risk Factors: The LC group showed more favourable improvements in triglycerides, HDL, Triglyceride:HDL ratio. The LC group also had more improvements in fasting glucose, fasting insulin and a reduction in small LDL particles.

20. Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo
Grant D Brinkworth, Manny Noakes, Jonathan D Buckley, Jennifer B Keogh, and Peter M Clifton – Am J Clin Nutr 2009;90:23–32.

Details: 118 obese individuals randomized to either a low-carb or a low-fat diet for 12 months. Both groups were calorie restricted.

Weight Loss: The LC group lost 14.5kg of weight, while the LF group lost 11.5. The difference was not statistically significant.

Risk Factors: Compared to the LF group, the LC group increased HDL, Total and LDL cholesterol and decreased triglycerides.


21. Efficacy and Safety of a High Protein, Low Carbohydrate Diet for Weight Loss in Severely Obese Adolescents
Nancy F. Krebs, MD, MS, Dexiang Gao, PhD, Jane Gralla, PhD, Juliet S. Collins, MD, and Susan L. Johnson, PhD – J Pediatr 2010;157:252-8.

Details: 46 severely obese adolescents randomized to either a low-carb, high-protein diet or a calorie-restricted low-fat diet for 13 weeks.

Weight Loss: The LCHP group lost significantly more weight and had a significant reduction in the BMI-z score compared to the LF group.

Risk Factors: Both groups improved Total cholesterol and LDL cholesterol levels. HDL levels decreased in the LF group, while Triglycerides decreased in the LC group.

The Studies

I went through all of the studies, took me about a week.

Weight Loss on Low-Carb vs. Low-Fat Diets

Weight loss is, almost without exceptions, greater on low-carb diets although the difference isn’t always statistically significant.

This effect is especially evident when the low-carb group is allowed to eat until fullness while the low-fat group is calorie restricted, which is how these diets are usually prescribed in practice.

When both groups eat the same amount of calories (isocaloric), the low-carb groups still tend to lose more weight but the effects aren’t large enough to reach statistical significance.

Part of the reason for greater weight loss on the low-carb diet given that calories stay the same may be increased water loss.

Weight Loss

Calories, Carbs, Fats and Protein

When the low-carb group is not calorie restricted but the low-fat group is, they tend to end up eating a similar amount of calories. Interestingly, calorie restricted low-fat dieters also end up eating a lower total amount of carbohydrates.

Another interesting observation is that on a low-carb diet, people don’t necessarily end up eating more fat than they used to. In fact, they tend to eat similar amounts of fat as they were before starting the diet.

Protein intake is higher on the low-carb diet, which may explain some of the increased satiety.

Appetite And Hunger

Low-carb diets tend to decrease appetite and hunger.

This is the main reason people lose so much weight without portion control or calorie restriction, they simply don’t want to eat as much.

Compliance and Attrition Rates

The studies where the LC diets are most effective are where people manage to follow them completely and restrict carbohydrates accordingly.

However, as with every weight loss diet, compliance is an issue and people tend to increase their carb intake over time. As carb intake increases, weight loss tends to slow down and some people even start gaining weight back.

This implies that weight loss on a LC diet (as with any diet, really) requires people to stick with it for life.

Attrition rates tend to be lower on LC diets (more people make it to the end) despite arguments by dietitians about LC diets being harder to stick to because they eliminate entire food groups.

This is probably due to the fact that people can eat until fullness and don’t have to be hungry all the time, which is common with calorie-restricted low-fat diets

The idea that low-carb diets are harder to follow is a myth!

Completed The Study

LDL and Total Cholesterol levels

Low-fat diets tend to decrease both Total and LDL cholesterol, but mostly in the first 3 months or so. Then they tend to go back up.

It is not true that low-carb diets raise LDL or Total cholesterol levels. The fact is that they remain pretty much the same. They don’t get any higher than before, although there is some individual variation here.

This is probably nothing to worry about, as low-carb diets tend to change the LDL pattern from small, dense LDL to large, fluffy LDL which is benign.

HDL Cholesterol levels

HDL cholesterol (the “good” cholesterol) usually goes up substantially on a low-carb diet, while it tends to increase less or even go down on a low-fat, high-carb diet.


Blood Triglycerides

Blood triglycerides always go down on low-carb diets, while they tend to decrease less, stay the same or go up on calorie-restricted low-fat diets.


Blood Pressure

Blood pressure seems to decrease for both low-carb and low-fat dieters and the difference usually isn’t significant between groups.

Glucose, Insulin and Type II Diabetes

Glucose and insulin tend to decrease further on low-carb diets in non-diabetics, but it is not always statistically significant.

In type II diabetics, glucose and insulin levels decrease much more on low-carb diets and the patients are often able to eliminate or drastically reduce medication.

This implies that these diets may be particularly useful for those with diabetes or impaired glycemic control.

Adverse Effects

There are some mild side effects of low-carb, ketogenic diets that are usually over in a few days. These include headache, nausea, fatigue, insomnia and constipation.

There are NO serious adverse effects of low-carb, ketogenic diets, despite the scare tactics (lies)!

Time to Retire The Fad

Low-carb, ketogenic diets are superior to low-fat diets, not only when it comes to weight loss but also in improving pretty much all the major risk factors for western disease.

The results of the studies above all point to low-carb diets being superior when compared to low-fat diets. This is especially prominent for obese individuals, diabetics and those with the metabolic syndrome.

Low-carb diets lead to much more weight loss than the standard of care, low-fat calorie restricted diets, without causing hunger. This is important, because being hungry all the time has a significant effect on quality of life and is hard to sustain.

Low-carb diets also improve other risk factors for disease further than low-fat diets, especially Triglycerides, HDL and LDL pattern.

Low-carb diets are the easiest, healthiest and most effective way to lose weight and reverse metabolic disease. This is a scientific fact.

It is time to retire the low-fat fad!


  1. ProudDaddy says:

    Once again, I am very impressed by your research and will be printing and filing this article. (If you knew how frugal I am (wife says “cheap”), you would realize what a high compliment that is!)

    One of the reasons I follow a low, but not very low, carb diet is a fear of hypothyroidism. This is based solely on anecdotes from the blogosphere, and I’ve been meaning to do some proper research. Have you encountered any solid data about this?


  2. Hugi Thordarson says:


  3. Katharine says:

    Really interesting research, and a joy to see someone tackling the evidence and not just relying on what the food industry tell us! BUT please don’t tar all veggies/vegans with the same brush – I am veggie AND eat a low carb diet (it’s not impossible). I simply choose not to eat meat – my choice. PS. any thoughts about the new evidence coming through re. fasting?….

  4. Thanks Kris for summing up all this data. I understand it must have taken a few hours. You´ve obviously put a huge amount of work into this.

    Looking at weight loss, lipids and metabolic parameters, low carb diets certainly do not appear inferior to low fat diets. On the contrary, low carb even appears to do better in many of the studies. However, somebedy might point out that most of the studies are small and long-term follow-up is lacking.

    Scientific studies as well as clinical experience has convinced me that a large proportion of people with overweight, obesity and the metabolic syndrome can improve their health by adopting a low carbohydrate diet.

  5. I tried to follow Atkins but failed. After a few days it just didn’t feel normal. I lost 1/2 kg each day for first 6 days and then weight loss stopped completely. All I had is just discomfort from constipation. My husband was even less lucky with Atkins – he actually didn’t lose any weight at all despite suffering for about 10 days. I still think low-carb is a good idea but Atkins induction is definitely extreme. I also go to the gym and work out regularly. After a few days I couldn’t perform.

    Don’t misunderstand me, I really like low-carb idea, but I just don’t agree that it’s so easy. You are allowed to eat till you are full but you won’t eat because all you have is meat or eggs and you are already constipated! If you look at further stages of Atkins he says that most people can eat about 60 g of carbs without gaining weight but I don’t think it’s realistic.

    I really think people are different and some approaches will work better with some people while something else works for others.

    • ProudDaddy says:

      I looked at one of Kris’s studies (Volek, 2004) because I was interested in the supposed non-change in REE. It turned out the non-change was in REE per unit of (new) mass (the best that could be expected) and still a surprise. However, the study argued for a “metabolic advantage” indicating some bias on the part of the researchers, an assertion that I don’t believe has ever been confirmed in metabolic ward studies.

      Anyway, the study was nice enough to plot some results by individual, and the differences were huge! No wonder the only statistical significance was for men. And if you disregarded a few outliers, you wouldn’t be able to conclude much of anything.

      So, yes, Elena, we are all different. Don’t believe the proponents who insist you must be doing a diet all wrong to not get the same results they did.

    • I got constipated badly the first time I tried Atkins, that was in the 90’s, but if you get the New Atkins for a New You book, I think you will see a big difference in how it is laid out now, There are more veggies in the first two weeks. Also, drinking lots of water is really important, that’s where I went wrong the first time! There are several versions of lo carb lifestyles now, so you can feel safe having another go!

    • The best diet for you is the one you feel good on and is sustainable for you in the long-term. Low-carb isn’t for everyone.

      That being said, some people eat 100-150g of carbs per day and do great. Going as low as 20g definitely isn’t necessary although it can really speed things up and some people prefer it.

      It’s important to experiment, and figure out what works best for you.

    • Jonathan Swaringen says:

      You should check out The Art and Science of Low Carbohydrate Living, The Art and Science of Low Carbohydrate Performance, New Atkins for a New You, and the Rosedale diet.

      Rosedale is one of the major proponents of Ketogenic diets. Read this article and the comments.


      You may find many of your answers there.

      It generally takes around two weeks to adapt to fat burning. During this adaption you can be have different side effects. Also when on really low carbohydrates your body dumps sodium and excess water. Steve Phinney and Volek advise using boullion cubes or home made bone broth to make sure to get plenty of sodium as the excretion of sodium can raise the requirement from 2300 mg to 5000.

  6. Excellent research Kris. The low-fatters carry on about how BAD low-carb is without a shred of proof. I will be sending this article along to both sides. Thanks for the ammo. Loridae

  7. This is a good summary of the literature.

    Your discussions seem to be predominantly focused on the objective of “weight loss” but this need not be equivalent with a “healthy” diet or general well-being (or at the very least, some of us are not concerned with weight loss). I was wondering what your take was on the China Study and those alike which empirically promote whole-grain, plant-based diets for decreased risk of cancer, heart desease etc. There has been no long-term study (that I am aware of) which focuses on LC-diets or Paleo.

    • Well, the studies above did measure health markers like cholesterol, triglycerides, blood pressure etc. which imply that low-carb diets should lead to a reduction in many of the diseases of civilization like heart disease and certain forms of cancer.

      The China study, although impressive, was an epidemiological study. Such studies don’t really prove anything although they can give us ideas of things to study further.

      The only randomized controlled trial (way more reliable than epidemiological studies) I know of that compared a low-carb (Atkins) diet to a low-fat vegetarian diet (Ornish) revealed that Atkins was superior in every way. The Ornish diet actually fared worst.


  8. Kris,
    Absolutely fantastic post! I haven’t had time to go through the links you provided yet, but my question is whether you noted how the “low Carb” definition fit the diets in the studies? What were the subjects eating? In which if these studies did researchers actually measure “low carb” (i.e. 50 grams of carbs or less) vs. just comparing “lower carb” to higher carb diets? Thanks.

    • It differed between the studies. Many of them started with 20g per day (Atkins induction phase) then increased the intake over time.

      Weight loss seemed to correlate directly with carb intake. When people started at 20g they lost a lot of weight, quickly. When their carb intake creeped back up things started slowing down and in some cases they gained some weight back.

  9. After going through your archives I found that you have addressed some of my concernes in earlier posts. However, I would love to see a future blog from you where you address the China Study and the whole-grain plant-based diet as opposed to low-carb/Paleo. As you probably know, they are similar in many ways but there are some fundamental disagreements (mainly to do with animal proteins).

    Btw, your evidence-based approach makes your posts very impressive!

    • Thanks! I should definitely do a post on vegan diets and the china study some time.

      Vegan diets don’t resonate well with me and they don’t have a lot of actual evidence behind them. Avoiding animal foods also doesn’t make a lot of sense given our evolutionary heritage as omnivores.

      That being said, I believe they can work well for some people given the proper precautions to get all necessary nutrients. Different strokes for different folks.

  10. Excellently documented. Great article Kris!

    The reason medical science is often giving out wrong information when it comes to wellness and overall health is because all their studies are done on what such and such chemical (or whatever) does to a particular disease. They want to know how things affect diseases and their symptoms, not necessarily what brings the body to a state of health. The two are very different.

  11. I am a big fan of low carb and successfully live my life that way.
    But I do believe it has caused nasal congestion in me – or rather, something I am eating regularly is causing it. I’ve cut out as many fermented foods as I can in case it was an allergy but it is still present months later.

  12. Annie-Megan says:

    Hey Kris,
    First, thank you for your generosity. I learn a lot with your articles.
    Question: I noticed on almost all the graphics that weight tend to go up after 6 months doing the low carb diet… Why is that??? How come we cant continue to loose or at least maintain the weight we lost?
    ( sory for my bad english, I am Québecoise :))

    • It’s because people, on average, start increasing their carb intake again. It is a matter of compliance, which is an issue on any weight loss diet, not just low-carb.

  13. I need to know how the low carb could be negative for someone with heart problems, maybe too much protein, cholesterol? He also has diabetes. He is telling me his sugar is staying down, but his BP is higher than usual. Usually a really good BP. Please help! Or tell me where I can trust to look!

    • Low-carb diets tend to have positive effects on risk factors for heart disease, also for diabetics. That being said, you must keep your doctor involved before making any changes.

  14. Kris,

    Thanks for going to the work of pulling together those research articles. It is interesting to see these 2 popular dieting methods compared side-by-side.

    That said, as a person with high blood pressure and high cholesterol, I fail to see how this could be a good option for me. Primarily, I’m concerned about the fact that without a caloric reduction it’s telling you to replace carbs (the body’s preferred energy source) with fat. Specifically, from what I know, it encourages you to eat a lot of beef and dairy, which are both high in saturated fat. Again as I understand, diets high in sat. fat lead to high cholesterol. How is it that these studies show that eating a high fat diet lowers it?

    Also, I’m a strong believer in exercise being a part of any healthy lifestyle. I don’t think that any diet is going to be very effective at all without doing some regular cardio.When you cut down on carbs the body is left with protein and fat for energy, neither of which are good for quick bursts like you do at the gym. Also, you will be burning off more protein which the body needs for muscle regeneration.

    Lastly, I don’t understand how a diet that doesn’t involve lowering the caloric intake can be effective for losing weight. Your still taking in the same amount of energy so you’re not forcing your body to feed off it’s fat reserves to make up the deficit.

    I don’t know. I come from the camp that believes if you rub a Snickers bar on it and it feels better, then do it! And I have seen that this works for some people. I just personally couldn’t do it until I understood more about why it works.

    • Jonathan Swaringen says:


      It actually makes quite a bit of sense and there are many explanations for why this occurs in various books.

      Since you mentioned doing cardio I highly suggest reading either The Art and Science of Low Carbohydrate Living and/or The Art and Science of Low Carbohydrate Performance and Body by Science.
      Both of the first books will give you a good explanation for why cholesterol and blood pressure are improved on a high fat diet.

      The second book will explain what the best exercise is and tons of reasons why.

      Part of the reason is because when you have a diet that is high in saturated fat and low in carbohydrates you are using your fat for fuel. People who are using their fat for fuel have lower levels of saturated fat in the blood because large amounts of it are being burned for fuel.

      There are much more detailed examples in the books.

  15. Kris,

    Nice job on all the research! I’m currently reading The Art and Science of Low Carbohydrate Living (the book Jonathan mentioned above) and I’ve found it highly informative and convincing that low carb diets are superior to low fat diets. Even if you don’t need to lose weight, you will benefit from becoming fat or keto-adapted and disease prevention.


  16. There is one more issue that I want to share with you concerning low carb vs. low fat and heart disease. The studies generally show that low carb lowers triglycerides and raises HDL-C which is considered positive. The effect on LDL-C seems to be small and a low fat diet is probably to be preferred if lowering LDL is the main target.

    However, we have to keep in mind that individuals respond differently. In my practice I have seen huge increase in total cholesterol and LDL cholesterol in people on a low carb high fat diet. This is not the rule, but it happens and it is a bit hard to predict who will respond in this way. It is likely, for example that people with familial hypercholesterolemia might show this type of response. Those who believe that cholesterol and LDL don´t matter will probably not worry about this and may even point out that particle size and particle number matter more than LDL-C. However, we cannot totally ignore LDL-C and if it goes up much on a low carb high fat diet I usually recommend cutting down on saturated fats and cholesterol. Possibly a Paleo type diet might be a better option in such cases.

    So keep in mind, although science is helpful, that individual responses to different diets vary a lot. However, don´t misunderstand me, I generally consider low carb to be helpful for people with overweight, obesity or the metabolic syndrome.

    • Jonathan Swaringen says:

      I’ve seen people speak of lowering their cholesterol that had Familial Hypercholesterolemia. This may not be true in all cases…but also not all cholesterol is bad. In some of the possible cases where cholesterol goes up its either temporary or most of it is benign. Recently there was research that showed that some HDL even can be “bad”. As long as you have the right kinds of HDL/LDL and low Triglycerides you should be good.

      There should be no cause for concern at a momentary increase if your losing weight….if your losing weight you are burning a ton of fat…which will release cholesterol. More will be in the blood when losing weight.

      In all the studies I’ve seen a real low carbohydrate diet…with good fats…either raise some types of cholesterol while lowering triglycerides and the pattern B LDL ie that bad ones.

  17. After reading Gary Taubes’s “Why We Get Fat and What To Do About It” over and over again, especially the part where he describes the almost-compulsory use of low-carb diets to treat obesity before WWII, I’m convinced that our nation’s dietary policy was changed to the heavy promotion and the of subsidized foods solely to provide boost to our economy–I believe it’s called “demand creation.” Today, as more and more people buy less and less of the stuff, we’ve taken to selling it overseas just to stay in business. As well as exporting food, we’re also exporting the sickness that goes with it (again, to boost the economy–for food producers and Big Pharma), when all it would take is a shift in industrial farm practices here at home for demand to resume, and sickness to subside.

  18. This is a tremendous amount of work done to summarize the latest research on this topic. Thank you for doing it.

  19. Hi Kris,
    I came across your website last week, and have found it to be very helpful. I am eager to begin a low-carb/low-sugar diet, not only to lose weight but to improve overall health. My problem is this: 5 months ago, I suffered from an episode of actue pancreatitis. I was rushed to the ER, and spent 3 days in the Intensive Care. By God’s grace, my condition was not as severe as some others who suffer from pancreatitis. Nobody knows what triggered it. I have drank minimally maybe 3-4 times in my entire life (I’m 23), and have since March stopped completely. I know of no family history, wasn’t really sick before that … Anyway, since then, I have recovered, but still have a hard time digesting fats. I usually experience bloating and abdominal discomfort even after the inclusion of very little fat in my diet. My diet up till now, and especially after the pancreatitis episode has been quite carb heavy and “low-fat” everything. “Low-fat” products actually help me, because I don’t have the bloating or gaseousness after meals, but I’m not too keen on the high sugar content in these products. Just wondering if you had any advice for someone in my position who would like to begin a low-carb/high-fat diet, but is somewhat limited? Thank you in advance!

  20. Awesome job Kris, thank you for taking all the time to compile the studies. Bookmarked for future reference.

  21. There are vast differences in what one describes as a low carb diet. Atkins and south beach are vastly different in approach and foods allowed yet both called low carb. There are innumerable studys showing disease prevention benefits of plant based diets. I’ve never seen research showing benefits of high meat diets. In fact there’s an inverse relationship between meat servings per week and health. Iyou need to clarify the types of foods consumed and how many grams carbs each study considered to be low carb. I think everyone agrees that diets low in processed foods is beneficial. But if you’re suggesting that high protein diets (especially in the form of meat or animal products) are healthiest, you need to do more research or at least clarify and define low carb. Ive seen many individuals have massive heart attacks several years after trying high protein low carb diets. Be cautious about encouraging people to go low carb because the average non nutrition professional will think they need steak instead of a sweet potato. That could be a travesty long term.

    • Uhh…

      “I’ve never seen research showing benefits of high meat diets.”

      The low-carb studies mentioned above are high meat. There’s your research.

      In the only study (a large-scale randomized controlled trial) where a plant based diet (Ornish) is compared to a low-carb diet (Atkins) – the low-carb diet came out ahead on EVERY marker measured. See here: http://www.kriskris.com/low-carb-vs-vegetarian-diet/

  22. My friend, it would benefit you to take a course on how to interpret research. You mis-extrapolating data to fit your pre-existing idea. That is a huge contrast to exploring research unbiasedly to gather information. It would take too long to teach you the pit falls and errors of you “conclusions” so i wont waste my time. However, because i care about people and their rusk for deadly chronic disease, i again implore you to take a closer look at that research and also research what types of diets contribute to the development of chronic disease before you claim something to be “the truth”. And again i will say, high meat diets have been proven indisputably to have an inverse relationship to long term health. A reduction in Calories over all can lead to a temporary drop in cholesterol numbers, if your using that to fuel your claim. Of course temporary is the magic word. There are numerous other biomarkers that contribute. Low processed carb is great, high meat is risky. Good luck to you.

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