Diets and Weight Loss

by Panos Prokos, MS, CSCS

The subject of dieting and weight loss continues to be an area of great controversy for most people. Over the past 20 years we have witnessed an evolution in the way of the nutritional approach to weight loss. Starting with the early 80's diets such as the Cambridge, the Beverly Hills diet, and the Scarsdale and continuing with the most recent ones such as the Atkins or the South Beach, the nutrition industry has been promising us presumably easy ways to achieve the body of our dreams.
It would seem logical that with so many promising diet options, the problem of obesity should have been eliminated, yet as of this writing the United States ranks first in the world in obesity reports with 61% of the population meeting the US Surgeon standards for overweight and 18% classified as clinically obese. In the following paragraphs we are going to take a brief look at the most popular of today's diets and hopefully help clear up some misconceptions and misinformation about nutrition and weight loss.
Despite the great number of today's diets, all of them can be divided into two main categories: The calorie restriction diets and the so-called carb restriction diets. Lets take a more detailed look at each category.

The calorie restriction diets

Here we have diets such as Weight Watchers and Slim Fast. They are all based on the main law of energy conservation which in simple terms states: Energy in equals energy out. Lets take a closer look: In very simple terms each gram of food we consume contains an amount of energy which our body will use to carry out its everyday activities (such as walking, driving, etc.) Therefore, the more food we consume the more energy we make available to our body for carrying out these tasks. It also makes sense that the more tasks we do, the more energy we will need to get from our food. For example, a carpenter whose task requires a lot of energy will have to eat a larger amount of food than a sedentary individual whose job does not require as much.

Here is where things get interesting: If we consume more food that our body requires for its everyday tasks, it will be converted into fat and stored for later use. Hence, if we want to loose weight we have two solutions:
1. Consume less food (and therefore less energy)
2. Do more work (and therefore use more energy)
Calorie restriction diets are based on the first solution. The calorie is used here as a measurement of energy. The less food we eat the less calories we get and by having no excess calories we avoid them being turned into fat.
Exercise (especially aerobic) is based on the second solution. The more time we spend on the bike or the treadmill the more calories we burn. These calories are hopefully coming from our fat stores and help us trim down.

Theoretically this sounds simple enough but in practice things do not work out this way. Apart from fat, our body has many other energy sources and our metabolism (the process of converting food into energy) is very selective in which of these sources it uses. In very simple terms, it does not immediately look into our fat storage for energy. Therefore when we are pedaling the bike, there is no guarantee that our body is braking down the fat cells to derive the energy. It may be using the glycogen stored in the liver or even worse braking down our muscle tissue and converting it into energy (a process known as gluconeogenesis). I will not get into more details here as I have discussed the metabolic process in many of my other articles.

The carb restriction diets

Diets such as the Atkins or the South Beach, try to circumvent the problem of energy source selection by using a metabolic approach. The hope is that by restricting carbs from the diet, we eliminate the body's option to use them as energy sources and therefore force it to use the fat stores for this purpose. The problem is that the body has one more resource left as we mentioned above, the precious muscle tissue. It can actually break it down for energy synthesis (gluconeogenesis). So once again we are not sure if we are burning fat when we pedal the bike or run the treadmill. There is a strong possibility that we are breaking down muscle tissue leaving fat untouched.

The solution: A synergistic approach

A synergistic approach to weight loss is comprised of three components: Nutrition, resistance training and aerobic exercise. A balanced nutrition consisting of all food groups (protein, fat and carbs) in amounts and ratios specifically designed for each individual, becomes easier to adhere to, and avoids the side effects of the diets. Furthermore, it becomes much more convenient to incorporate into our busy schedules and therefore increases our chances of adhering to. Resistance training helps build and/or maintain muscle mass, which is invaluable as muscle is the place where fat gets burned. The mitochondria of the muscle are the places where fat gets converted to energy. Therefore the more muscle we have, the more mitochondria available and the more fat we can burn. Aerobic exercise when kept in moderation and done correctly (i.e. within the recommended heart rate percentages) aids to the fat burning process. A good nutrition program as part of the synergistic approach, stimulates metabolism, provides all the nutrients needed for health, and becomes much easier to adhere to in the long run.