With the increase of fad diets in the media the constant questions seem to be “what are my macros” or “what ‘superfoods’ should I eat” and “what foods should I avoid.” These questions are a direct result from most fad diets falling into the low-carb or low-fat spectrum. For example, several diets sensationalize the restriction of carbohydrate intake. The keto diet, for example, is very high in fats, low in proteins, and very low in carbohydrates. The Atkins diet is high in fats, high in proteins, and very low in carbohydrates. The “paleo diet” (hunter-gatherer diet) is high in fats, high in proteins, and low in carbohydrates. In essence, these diets establish rules around what and how to eat as a means to reduce caloric intake but are they the best rules to follow?
Why does it seem a universal rule the reduction of carbohydrate? Proteins and fats digest slower than carbs and are thus more satiating. Also, many of these diets recommend the consumption of foods that are less calorically dense and more nutritionally dense (more vitamins, minerals, fibers, and higher water content), i.e., a pound of veggies packs fewer calories and more nutrition than a pound of Oreos. Many of the calorically dense foods contain added sugar and carb sources such as the mentioned Oreos. Additionally, research shows that the synthesis of serotonin from carbhydrate may cause cravings for some obese people.
However, science shows that bodyweight depends on total caloric intake more than the ratio of calories come from carbohydrates, proteins, fats, and alcohol. Excessive caloric intake as an independent variable is more than sufficient to explain the obesity epidemic, without the need of a scapegoat, such as high-fructose corn syrup. For example look at endurance athletes who have such high-calorie needs that they often utilize high carbohydrate and calorically dense foods in training and racing.
A controled study conducted in a metabolic ward compared several diets composed of 15% protein, 15-85% carbohydrate, and 0-70% fat. It concluded that caloric restriction determined weight loss, not macronutrient ratios. Comparing low- and high-carbohydrate diets over six weeks and twelve weeks led to the same conclusion, as did comparing a low-fat/high-protein diet with a high-fat/standard-protein diet. Addionally an eight week trial in a metabolic ward noted that caloric intake alone accounted for the increase in body fat when healthy individuals overeat.
Why the craze over keto diets? People on low-carb diets lose weight because they naturally eat less and avoid the massive binges caused by carbohydrate cravings. People on very-low-carb diets can also lose weight very quickly on the short term because the depletion of their glycogen stores leads to the excretion of bound water. That explains why two trials found that people on a low-carb diet had lost more weight than people on a low-fat diet after six months but not twelve meaning that initial weight loss gains were the result of reduced water weight.
In conclusion, losing weight requires a negative energy balance which fluctuates each day based on activity. Once energy needs are estimated a negative balance is achieved by eating less, as we have seen, or by exercising more. Estimations on daily energy needs outside of a lab are merely a guess, and for this reason, most healthy individuals are served better by following a few simple rules. First, listening to the body’s hunger and satiety cues or eating to 80% full. Second, eating a moderate and varied diet of nutritionally dense vs. calorically dense whole foods such as lean proteins, veggies, smart carbs, and healthy fats. Lastly, eating with awareness through eating slowly and using food journals.