Shahar Madjar, MD

Almost everyone wants to lose weight but only few of us have a deep desire to cut the amount of food we consume.

And why would we have such a desire?

After all, food is abundant, comforting, and tasty. It is a source of pleasure and of meaning. It is therefore tempting to ask: can we lose weight not by decreasing our caloric intake but by changing the composition of our food — by controlling the relative amounts of macronutrients such as carbohydrates, proteins and fats in our diet?

In the typical American diet almost half of the calories (47%) come from carbohydrates, 36% of the calories come from fat, and 16% of the calories come from protein. Diets that aim at controlling macronutrients typically belong to one of three groups: you either restrict your carbohydrates (low-carb diets), your fat consumption (low-fat diets), or you focus on increasing your protein consumption (high protein diets).

The most popular diet programs calling for manipulation of the relative amounts of macronutrients are those that recommend a decrease in the amounts of carbohydrates. There is a logical explanation for why limiting carbohydrates should work: ingestion of carbohydrates leads to an increased insulin production — a hormone that directs fat toward storage in adipose tissues. Low carbohydrates diets, the theory goes, will lead to a reduced insulin production and an increase in the level of another hormone, glucagon. The combined effect would lead to a shift of fat away from the adipose tissues and toward higher fat oxidation, or, in other words, a shift from fat accumulation into fat burning. This theory has been described as the Carbohydrate-Insulin Model of Obesity, and like all theories, it should be viewed as a mere theory unless scientists and doctors can actually prove it.

Two popular low-carbohydrates diets are the Atkins diet and the ketogenic diet. In both diets the amounts of carbohydrates is severely restricted, and most of the calories are consumed in the form of lipids and proteins. The main difference between the diets is this: on the Atkins diet the amounts of carbohydrates is gradually increased as the diet progresses while on the keto diet, the amounts of carbohydrates remain stable and very low (5-10% of the total daily calories come from carbohydrates). Another difference is that the Atkins diet calls for more protein consumption (25% of the total calories) and lower lipid consumption than that on the ketogenic diet.

The Ornish diet (developed by Dr. Dean Ornish) is an example of a diet rich in carbohydrates and very low in fat. Up to 70% of the calories in the Ornish diet comes in the form of complex carbs, fruits, and vegetables. Refined, processed carbs are discouraged. The diet also allows for limited amounts of non-fat dairy products and egg whites, but no meat, poultry, or fish.

Two popular high protein diets are the Zone and the Paleo diets. In both, 30% of the calories come from proteins. The Zone diet is less restrictive in the variety of food that can be consumed. It emphasizes portion control and aims at avoiding spikes in insulin release. It calls for 3 meals and 2 snacks a day (five meals, no longer than 5 hours apart), and focuses on proteins and on carbohydrates with lower glycemic index. The Paleo diet (short for Paleolithic diet), on the other hand, advises participants to consume food that mirrors the diet eaten by humans during the Paleolithic era. So if there is a hunter-gatherer hiding in your heart, this is the diet for you.

If your head is spinning from the plethora of diets, the difference in their philosophical origins, and the wide variety of food allowances and restrictions they suggest, don’t fret. You aren’t alone. The subject is highly complex and quite confusing. And in the end, the questions that

matter are: How effective is controlling the macronutrients in your diet? Is it worthwhile to restrict your diet based on the content of macronutrients? Should you embark on Atkins, Keto, Zone, or Ornish diet? I will attempt to answer these questions in my next article.