Part 10

Basic Weight Loss Diets (Good and Bad)


What ALL effective (dangerous and safe) Weight Loss Diets Have in Common:

All diets that actually work do so because they produce "net calorie deficit". In other words, they cause people to burn more calories than they consume either by reducing consumption, increasing output or both. This isn't a fact that has been determined by experiment, it is an axiom, an inevitable truth based upon the meanings of the terms "input" and "output".


Macronutrient Restriction

As we have seen elsewhere, there are three macronutrients: fat, protein and carbohydrate. Protein cannot be safely restricted; we require at least 50-75 grams of high quality protein daily or we begin to burn up muscle tissue. Carbohydrate OR fat can however be safely restricted and indeed low carbohydrate and low fat diets are two popular approaches to weight control. Both work and both have the virtue of using calorie SOURCE to their advantage. In every other sense however, low carb and low fat diets are polar opposites. They both deserve some discussion.

Low Carbohydrate Diets

The idea of using carbohydrate restriction to promote fat loss dates to at least the mid 1960's in the US. They were very popular at that time and through the early 1970s but then fell into relative disfavor after receiving a good deal of bad press from the medical establishment of the day. Low carb diets re-emerged on the American scene in the late 1990's with the publication of a book called "Dr. Atkins' New Diet Revolution" which advocated for a very low carbohydrate "induction" diet followed by a more moderately-low carbohydrate 'maintenance' phase.

As in the 1970's the initial reaction of the American medical establishment to the millennial Atkins diet craze was negative. Many doctors, myself included, were convinced, largely by our training, that low carbohydrate diets were dangerously high in fat and protein. I graduated medical school in 1989 fully indoctrinated by the "Framingham Heart Study" that launched our modern understanding of the relationship between cholesterol and heart disease. Diets that advocated consumption of large amounts of red meat and fat seemed crazy; twelve years later, not so much.

Low carbohydrate diets have their place in weight control. They work, they are safe in the short term and, research is starting to show, they are likely safe in the longer term. I am still not sure how livable they are for most people, but certainly some people find low carbohydrate diets satisfying in the long-haul.

The real legacy of the low carbohydrate craze may be that it showed people an easier way than starving or counting calories and that it 'helped' a lot of us physicians to reevaluate our understanding of nutrition.

Low Fat Diets:

Weight loss through fat reduction has a lot of appeals. First, fat is THE calorie dense nutrient (9 calories per gram versus 4 and 4 for carb and protein) so that people can eat more non-fat food, a lot more in fact, and still consume fewer calories. Also, we know that fat has the lowest 'thermic effect' (2-3% versus ~10% for carb and ~ 30% for protein). Finally, much of the human race normally consumes very little fat and seems to stay thin and healthy without many of the chronic diseases that plague affluent western nations like the US.

I began practicing bariatric medicine in 1991 as a staunch advocate of very low fat diets for weight control and while my views today, nearly twenty years later have changed, I still believe that fat reduction is an important component of a sensible long-term weight control plan.

The main drawback to low fat diets is that they don't keep people feeling full for very long so that to be livable, they require people to eat quite often.

Final Thoughts on Macronutrient Restricted Diets for Weight Loss

Macronutrient restriction is a more sophisticated approach to weight loss than simple calorie reduction because it alleviates the burden of having to focus on amount of food consumed (with the inevitable result of having to go hungry) and instead shifts people's attention to the composition of the food. Macronutrient restricted diets are easier than calorie restricted diets, they work and are safe.