I am frequently asked the question of “what is the best diet for weight loss?” One need only open any current magazine, flip on the television, or ask the person next to you at the beauty salon, to find a different recommendation for the best and safest diet for weight loss. The media is replete with multiple products, methods and claims to take off weight and to keep it off. Often this is accompanied by a specific product, nutrient or proprietary device that is essential to accompany the program. But does it all work? What does the science and the research show?
I think that the ultimate solution to weight loss is tripartite; resting on the pillars of caloric intake, macronutrient distribution, and finally (and most commonly missed), a functional consideration of the factors leading to the improper metabolism and storage of calories. I know that this sounds a bit vague, but trust that all will be clarified in the following paragraphs. What is problematic however, is that in reviewing the primary scientific articles to address the question of obesity and what is required to rein in our battle with the bulge, I am unable to find one that addresses all three of these pillars together. There are studies comparing caloric intake and weight loss, as well as the effects of different macronutrient distributions in terms of percentages of fats, carbohydrates and proteins. Some of the studies have looked between these groups, comparing calorie restriction in groups of patients utilizing either high fat, low fat or low carbohydrate diets.
The permutations are vast, and generally the results are confusing. I have found, however, a few well designed trials in the literature that help me to make my recommendations to my patients.
So regarding the question, “is calorie restriction important in a weight loss program?” I would answer yes, but mark that with an asterisk.
A nice study was published in the prestigious New England Journal of Medicine in 2007 that compared reduced calorie diets with different ratios of macronutrients over a two year period. In this reduced calorie trial, all three diets showed an average of 13.2 pounds lost at 6 months. At the end of the trial, of the 80% of participants who completed the trial, the average weight loss was 10 pounds, with 15% of the participants losing a full 10% of their body weight.
I think that the size of this trial (811 patients) makes the results pretty compelling. However I still believe that if an individual sticks with the right type of food, that significant calorie restriction isn’t needed.
But here’s the asterisk. Once we allow ourselves to become more cognizant, more aware of the foods that we are eating, a reduction of calories simply follows suit. I typically don’t make specific recommendations for caloric intake with my patients. I think that if the nutritional intake consists primarily of healthy fruits, vegetables, an emphasis of vegetable-based proteins, nuts, and limited but healthy grains, there is no need to impose a direct limit on caloric intake. Our bodies impose their own limits once the right food is ingested, and the wrong foods are limited. So here is my first recommendation: It’s the quality of the food, more than the quantity of food, that allows us to maintain a healthy body weight.
But what about the macronutrient composition of our foods? I believe that here there is some interesting research that sheds some light on the effect that the distribution of carbohydrates (sugars), fats and proteins have on our metabolism and ability to shed weight.
The A to Z trial referenced below compared the Atkins, Zone, Ornish and LEARN diets in overweight postmenopausal women.
Weight loss at 12 months was the primary outcome. The weight loss was greatest with the Atkins diet and the Zone diet- both diets emphasizing low carbohydrate intake. The Atkins diet pushes more towards a carbohydrate restricted diet, while the Zone diet allowed more carbohydrates, but stressed increased levels of the healthy fats found in fish oils. There was no change between the Zone, Ornish and LEARN groups.
I personally believe that a low carbohydrate diet, emphasizing the low meat intake, healthy oils, fish, and high fresh vegetable intake of the Mediterranean Diet really makes the most sense. And there is good data to prove it.
A nice paper was published in the New England Journal Of Medicine in 2013, looking at “primary prevention”, or prevention of an initial heart attack or stroke, with the Mediterranean Diet. This trial was large, with 7500 men and women enrolled, but was stopped after 5 years due to the powerful information gained in an interim analysis.
The trial showed that there was a 28-30 percent decrease in cardiovascular disease in the participants who consumed the Mediterranean diet, with or without nuts, relative to a control group. I find these findings, in part due to the statistical strength of such a large study, to be very compelling.
So I think that the data is pretty clear that there is a benefit in consuming a lower calorie diet, a lower carbohydrate diet like the Atkins diet, and a Mediterranean palette of food emphasizing healthy grains, fish consumption, vegetables, oils, and limiting but not eliminating the intake of meat.
But as you may sense, this is not the entirety of the formula for what needs to be addressed to reliably and permanently take off extra weight. This is where a functional perspective is essential to fill in the gaps in the evidence brought to light by papers such as the ones referenced above. All of the studies above appropriately stratified participants by standard metrics; age, weight, race and sex, smoking. For statistical analysis they either included or excluded known factors contributing to weight gain, such as thyroid disorders, diabetes and other medical factors such as cardiovascular disease or kidney dysfunction.
But I can assure you that none of the large studies that have been developed to evaluate diet and weight loss evaluated the input of the adrenal gland, which produces cortisol, the primary regulator of energy storage in the body Nor did they look for the presence of heavy metals, or the organic toxins found in pesticides or herbicides, substances again well known to disrupt enzymatic and endocrine systems. To my knowledge none of the studies evaluated weight loss in the face of hormonal balances, bowel microbiology, or the ability to detoxify. In short, all of the studies were stratified in the usual means of age, weight, sex, race….. but many factors known to contribute to metabolism and weight gain were never considered in the analysis.
In conclusion, I recommend a three-pronged approach to my patients that promotes mild, tolerable calorie restriction. Simple instructions such as not feeling a need to polish off the plate, or stopping eating when 80% full will invariable suffice. I recommend to my patients that they focus not on counting calories, but on learning to read labels, and to understand what is in the food that we are eating. Better yet, don’t read any labels. Use whole foods, colored foods and live foods. Change your diet from processed to whole foods, and weight loss will follow.
Secondly, I recommend a diet that follows the familiar “Mediterranean” style outlined above, emphasizing healthy fats, small portions of animal proteins such as meat, lamb and fish, with lots of colored vegetables, nuts and whole grains. And finally, and most importantly, your weight loss program must be considered with a functional eye. By looking closely at the energy production and storage systems of the body (adrenal, thyroid and pancreas), optimizing the detoxification pathways mediated through the liver and the gut, and by ensuring that the hormonal “symphony” is not “playing different tunes” (apologies to Pink Floyd), you will unquestionably regain your health, wellness, energy and figure.
Dr. Scott Resnick