Are low fat calorie restricted diets fueling the obesity epidemic and increased rates of heart disease? That’s the claim put forth by a recent meta review in the journal OpenHeart. The scientists state:
Focusing on total energy consumed, as opposed to nutritional value, has been exploited by the food industry, which has added sugar to over 80% of all processed foods. One can of cola contains nine teaspoons of sugar. The EPIC study revealed that one can a day (approximately 150 calories) was associated with substantially increasing the risk of developing type 2 diabetes.21 Conversely, PREDIMED revealed that consumption of a handful of nuts, (30 g of walnuts, 15 g of almonds and 15 g of hazelnuts) or four tablespoons of extra virgin olive oil per day (approximately 500 calories) significantly reduced the risk of heart attack and stroke. A recent randomised pilot study of a calorie unrestricted very low carbohydrate/high fat diet in overweight patients with type 2 diabetes or prediabetes resulted in a significant improvement in glycaemic control and even discontinuation of diabetes medications within 3 months in comparison to a moderate carbohydrate, low-fat calorie-restricted diet (consistent with guidelines from the American Diabetes Association), with no adverse effect on blood lipids.22 A critical review in Nutrition also concluded that dietary carbohydrate restriction is the “single most effective intervention for reducing all of the features of the metabolic syndrome” and should be the first approach in diabetes management with the very low carbohydrate ketogenic diet (<10% carbs) revealing the greatest falls in glycated hemoglobin and reduction in the use of medications with benefits occurring even without weight loss.23
While I agree with the majority of what this study claims, the final sentence here is a prime example of what happens when scientists ignore data that runs counter to their predispositions. In this case, they ignore data that shows a whole food, low fat, high carb, unrestricted calorie, vegan diet is far superior in controlling diabetes and weight management than a high fat, high protein, ketogenic diet.
If we look at the study being referenced to back their claims, we can see that they never bothered to include studies that cover a whole food vegan diet plan in their survey. Had they done so, they would have found studies such as these:
1. “Both a low-fat vegan diet and a diet based on ADA guidelines improved glycemic and lipid control in type 2 diabetic patients. These improvements were greater with a low-fat vegan diet.”
2. “In an analysis controlling for medication changes, a low-fat vegan diet appeared to improve glycemia and plasma lipids more than did conventional diabetes diet recommendations.”
3. “Despite its greater influence on macronutrient intake, a low-fat, vegan diet has an acceptability similar to that of a more conventional diabetes diet. Acceptability appears to be no barrier to its use in medical nutrition therapy.”
4. “Adoption of a low-fat, vegan diet was associated with significant weight loss in overweight postmenopausal women, despite the absence of prescribed limits on portion size or energy intake.”
5. “A vegan diet was associated with significantly greater weight loss than the National Cholesterol Education Program (NCEP) diet at 1 and 2 years. Both group support and meeting attendance were associated with significant weight loss at follow-up.”
6. “An 18-week dietary intervention using a low-fat plant-based diet in a corporate setting improves body weight, plasma lipids, and, in individuals with diabetes, glycemic control.”
7. “Appetite control and weight loss were similar for both HPWL diets. Gut hormone profile was similar between the diets, which suggests that vegetarian diets can be as effective as meat-based diets for appetite control during weight loss.”
8. “…uric acid kidney stones are 500-fold more frequent on the ketogenic diet and calcium oxalate stones are 50-fold more frequent.”
9. “In our meta-analysis, [low carb] LC dietary protocols were associated with a significant decrease in [arterial flow mediated dilation] FMD when compared with their [low fat] LF counterparts.”
10. “High [saturated fat] SFA caused deterioration in FMD compared with high [polysaturated fat] PUFA, [monosaturated fat] MUFA, or [high carb] CARB diets. Inflammatory responses may also be increased on this diet.”
And on and on and on…
I could probably list a 100 studies showing the negative impacts a diet high in saturated fats, such as a typical ketogenic diet, can have on arterial function. So while a ketogenic diet might help with diabetes due to its weight management qualities, the people consuming such a diet put themselves at increased risk of heart disease, which is exactly what they were trying to avoid in the first place. Any doctor recommending this kind of diet for something other than epilepsy cases is guilty of giving people terrible dietary advice.
I also dislike their focus on the use of fish as a source of omega 3 fats. While this may decrease heart disease risk, and is certainly better than red meat or poultry, fish are also loaded with toxins. NAVs reports, “Higher mercury levels in mothers who eat significant amounts of fish have been associated with birth defects, mental retardation, seizures, cerebral palsy, and developmental disabilities in their children. A U.S. Environmental Protection Agency (EPA) analysis released in 2004 indicated that about 630,000 of the 4 million children born annually in the U.S. are at risk of impaired motor function, learning capacity, memory, and vision – due to high levels of mercury in their bloodstreams.”
Further, fish don’t come with any of the protective phytochemicals that we find in plants. So while eating fish may give you a source of omega 3 fats, along with a source of protein, you could get those same benefits plus the additional benefits of fiber and lignans by eating flax seeds or walnuts, without the risk of disease or toxin poisoning that fish carry. Fish also have nearly twice the cholesterol per calorie as does beef. Fish are not part of an ideal diet. They are better than red meat and poultry, but not ideal.
It’s also worth noting that a recent metabolic ward study, where people are locked in a hospital ward and their diets are completely controlled by scientists, found that low fat diets were superior to high fat diets when it comes to weight loss. The LA Times reports:
The authors of a study published Thursday in the journal Cell Metabolism conducted a high-tech throw-down pitting a carbohydrate-restricted diet against a weight-loss regimen that reduces dietary fat. Confined for a total of four weeks in an NIH metabolism lab, research subjects got equal calories in each condition (low carb, low fat, each for two weeks).
The subjects in each condition also had equally scant opportunities to cheat, shave or misremember what they ate. Night and day, machines measured not only how much fuel their bodies were burning, but what kind of fuel.
In the end, the obese subjects lost weight regardless of which diet they were on (and low-carb dieters lost a little over a pound more than did low-fat dieters over two weeks). But obese subjects on a low-fat diet lost more body fat than did those on a diet low in carbohydrates.
This is as good as it gets when it comes to scientific data. The conclusions drawn from this study should be obvious. Fat has twice the caloric density of carbs or protein, meaning you can eat twice as many carbs as you can fat for the same amount of calories. And carbs loaded with fiber, such as fruits and vegetables, provide even an even more filling meal for less calories compared to other types of carbs.
Further, consumed fat requires virtually no metabolic processing before it is stored in the body as fat. Carbs have to be broken down and transformed into fat before they can be stored as fat, which gives the body a chance to burn off those calories before ramming them into fat cells.
Dr. Michael Greger discusses the effects of fat on the functioning of our arteries, specifically covering the effects of olive oil and the Mediterranean diet: