In the ongoing nutritional war between adherents of low-fat and low-carb diets, the skeptical cardiologist has generally weighed in on the side of lower carbs for weight loss and cardiovascular health.
I’ve questioned the vilification of saturated fat and emphasized the dangers of added sugar and I consider myself a keto-friendly cardiologist.
Recently I stumbled across a good review on the scientific evidence of various popular diets for weight loss. Obesity and its health consequences are clearly increasing and impacting the cardiovascular health of millions. As such, as a cardiologist it would be great to have a one true diet that is best for weight loss for my patients.
Unfortunately, as I discussed in my analysis of the DIETFITS study there isn’t a one size fits all dietary silver bullet. This recent review does a good job of analyzing the data and has some nice graphics.
Here’s the first graphic which summarizes the food groups allowed for 7 of the most popular diets
Is there any food group we can all agree on?
Yes, the non-starchy vegetables!
Dr. P’s Heart Nuts come in a close second (outlier Ornish recommends “moderation”. Extreme outlier Esselsytn who eschews all oils forbids nuts.)
Interestingly, the only one of these diets that bans red meat, chicken, seafood and eggs is the Ornish diet which is basically a vegetarian diet (see here for the lack of science behind this diet.)
Is there any food group that we all agree should be avoided? If we exclude the outlier Ornish then there is unanimity that we should be avoiding added sugar and refined grains.
My recommended version of the Mediterranean diet says that high fat dairy is perfectly fine and actually preferred over processed skim or low fat dairy. Yogurt and cheese are encouraged.
Do Macronutrients Matter?
The second graphic nicely summarizes the macronutrient composition of these diets. The Atkins diet and ketogenic diets recommend less than 10% carbs whereas Ornish the outlier recommends less than 10% fat.
My recommended variation on the Mediterranean diet would lower the carb % to around 20% by avoiding starchy vegetables, most added sugar and most refined grains. I try to avoid ultra-processed foods completely. With this diet I am in some degree of ketosis (as measured by the fantastic Keyto device) most of the time although I’m not strictly following keto guidelines.
For example last night I had this delicious steak and smoked portabello quesadilla from Three Kings Pub. The tortilla alone contains about 40 grams of carbs, double the recommended amount for keto diets. I add elements of Three Kings Middle Eastern Sampler (Red pepper hummus, grilled eggplant relish, tzatziki, roasted head of garlic and dolmas. Served with grilled flatbread and an assortment of veggies) to get some of those universally acclaimed nonstarchy vegetables . I don’t utilize the balsamic reduction that is typically drizzled on the quesadilla because it tastes like pure sugar to me (sure enough it contains 11 grams of carbs)and I mostly avoid the grilled flatbread.
Manipulation Of Diet Timing For Weight Loss
Breakfast is not the most important meal of the day and I only break my overnight fast when I get hungry which is typically around noon.
Variations on this type of intermittent fasting (periodic fasting or 5:2 diet, alternate-day fasting, time-restricted feeding, and religious fasting) have become popular. The review summarizes the science in this area as follows:
“There is growing evidence demonstrating the metabolic health benefits of IF. In rodents, these appear quite profound, whereas in humans they are sparse and need further investigation, especially in long-term studies. It has been suggested that IF does not produce superior weight loss in comparison with continuous calorie restriction plans , and there are limited data regarding other clinical outcomes such as diabetes, CVD, and cancer. IF diets seem safe and tolerable for adults…”
In other words, rats live longer with IF but we don’t know if humans do. If you find intermittent fasting helps you consume less calories through out the day and lose weight, go for it. For me fasting from 9 PM to late morning (typically 14-16 hours) give me greater energy and focus throughout the day and makes weight management simpler.
Conclusions: What Is The Best Diet For Weight Loss?
Both low carb and low fat fanatics will be disappointed in the conclusions of the review but I think it is reasonable:
There is no one most effective diet to promote weight loss. In the short term, high-protein, low-carbohydrate diets and intermittent fasting are suggested to promote greater weight loss and could be adopted as a jumpstart. However, owing to adverse effects, caution is required. In the long term, current evidence indicates that different diets promoted similar weight loss and adherence to diets will predict their success. Finally, it is fundamental to adopt a diet that creates a negative energy balance and focuses on good food quality to promote health.
And here is the summary graphic
N.B. With regard to the starchy vegetables, check out my “Potato Theory of Obesity.”
Source for images: Scientific evidence of diets for weight loss: Different macronutrient composition, intermittent fasting, and popular diets – ScienceDirect
And finally (from the DietDoctor.com website) a graphic that illustrates the amount of healthy (nonstarchy!) vegetables that you would need to consume to reach 20 grams of carbs.