Diet fanatics are everywhere.
People pick sides and defend them as if they were in a war.
Now I have nothing against vegan/vegetarian diets as I’m sure they do work well for some people.
But some of their proponents make claims that challenge both common sense and science.
One of those claims is that a low-carb, high-fat, high-protein diet that is rich in animal foods is either ineffective or dangerous.
They often claim that a low-fat vegetarian diet is the way to go, both ethically and for optimal health.
For optimal health, absolutely not.
Atkins (low-carb, high-fat) vs. Ornish (low-fat, high-carb, vegetarian)
We do have scientific evidence where a low-carb, high-fat diet is vastly superior to a low-fat vegetarian diet.
There was a fairly large randomized controlled trial published in 2007 comparing 4 different diets.
It was published in the Journal of The American Medical Association by researchers at Stanford university.
The other two diets are the Zone (a moderate carb diet) and LEARN (similar to the official guidelines).
The study went on for 12 months. For simplicity, I’m going to focus on Atkins (low-carb) vs Ornish (low-fat, vegetarian). The results for the Zone and LEARN were intermediate between the Atkins and Ornish.
The study subjects were 311 overweight/obese premenopausal women and it went on for 12 months. It has quite a lot of power compared to many weight loss studies because it is fairly large and has an outstanding compliance rate with about 80% completing the study.
The Study Details
Each of the groups received a diet book and detailed instructions.
The group following the Atkins diet received the book The Atkins New Diet Revolution and those following the Ornish diet received Eat More, Weigh Less.
This study is an excellent representative of real life results and typical of most dieters, because most people on a diet aren’t housed and fed. They go out, buy a diet book and do their best to follow the advice.
They measured weight and a whole bunch of risk factors at 2, 6 and 12 months.
Both the Atkins and the Ornish diet were allowed to eat until fullness.
At the end of the study period, the individuals following the diets had gravitated a little bit away from the guidelines.
The Atkins group had started to eat more carb (about 30% of calories, still fairly low) and the Ornish group more fat (about 30%, typical for standard guidelines).
The Results – Low-Carb vs Vegetarian Low-Fat Diet
The Atkins group lost more weight than the Ornish group. -4.7kg (10.4lbs) vs. -2.6kg (5.7lbs) at 12 months. The difference was statistically significant at 2 and 6 months, while almost significant at 12 months.
Other markers of health were significantly improved on Atkins compared to the Ornish diet:
HDL Cholesterol: The “good” cholesterol, HDL, improved by 4.9 mg/dL on Atkins while it didn’t change at all on the Ornish diet.
Triglycerides: Decreased by 29.3 mg/dL on Atkins compared to 14.9 mg/dL on Ornish.
Systolic Blood Pressure: Decreased by 7.6 mmHg on Atkins, compared to 1.9 mmHg on Ornish.
Diastolic Blood Pressure: Decreased by 4.4 mmHg on Atkins, but only 0.7 mmHg on Ornish.
A few other things had greater improvements on the Atkins diet, but weren’t statistically significant. These include glucose and insulin levels, along with compliance (88% on Atkins compared to 78% on Ornish).
LDL cholesterol improved slightly on the Ornish diet at 2 months, but the effect had pretty much diminished at 6 and 12 months and the difference was not significant.
Basically, there were several important advantages for the low-carb diet and there were zero advantages for the low-fat vegetarian diet.
Generally speaking, the Atkins diet did best out of all 4 diets on all parameters measured, while the low-fat vegetarian diet did the worst.
This is the only study I know of that compares a low-carb diet to a vegetarian diet head to head. Next time a vegan/vegetarian comes by with a condescending look and tells you you’re killing yourself with all that meat and protein, tell them about this study.
Christopher Gardner, the Vegetarian Lead Researcher
The lead author of the study, Christopher Gardner, is a 25 year vegetarian and a nutritionist.
In contrast with most of those who share these attributes, he chose the open-minded point of view and presented the results as they were (instead of sticking his head in the sand in denial, which is common for both vegetarians and nutritionists).
Here is a video where he presents the results of the study.