For years, the advice on how to lose fat from experts in the medical, health, and fitness fields has been eat less (diet), move more (go for a walk). The formula for fat loss was simply:
Change in Body Weight = 'Calories in' - 'Calories out'
However, as we know, the number of people who are successful with this method has been very slim (no pun intended). Is it lack of will power? Lack of motivation? Or, is it that this advice is flawed?
Well, it appears that the advice is flawed. While you will see some changes in your body weight if you follow a low-Calorie diet, inevitably, it fails in the long-run. The above equation is just too simplistic. In the equation, you can change one variable, such as decrease your 'Calories In' and you will see a small decline in body weight. But, most people will attest, your body weight will plateau fairly quickly. The body adapts; the equation changes. Here are some examples of how the equation can change:
Calories out' varies tremendously, even at rest.Resting metabolic rate fluctuates as a function of 'Calories in'. As you restrict your Caloric consumption, your resting Caloric expenditure will plummet. Additionally, your appetite will greatly increase. The body copes with a lower Caloric intake by lowering its energy expenditure and attempts to increase Caloric intake by increasing appetite. On the other hand, resting metabolic rate will rise significantly if you raise the 'Calories in'. side of the equation, and appetite will decrease.
The loss of body weight is usually not exclusively body fat.When you lose weight from a restricted-Calorie diet, the body meets its energy demands by breaking down skeletal muscle and converts it to glucose via gluconeogenesis (process of chemically removing nitrogen and converting amino acids to glucose in the liver). So, a significant amount of weight loss is from lean muscle mass. Concurrently, resting metabolic rate will drop, as it is directly related to muscle mass (which is an energy sink-uses lots of energy, especially if you workout regularly).
All Calories are not equal in their role in metabolism."It doesn't matter if you eat celery, cookies, or meat, a Calorie is a Calorie." Well, if you used food for energy outside of the body, this statement is probably true. However, we use different biochemical pathways to derive energy from various nutrients (fat, protein, carbohydrate, or alcohol) inside the body. Some pathways are more efficient than others to extract the energy in the chemical bonds of the ingested nutritive substances. For example, converting protein to glucose uses over 25% of the energy it would supply as glucose.
Hormonal control of nutrient availability determines what fuel can be used for energy.The body maintains very precise levels of nutrients in the blood based on its needs. Fatty acids and glucose are included. They are finely regulated by a variety of hormones. Interestingly, the composition of the diet and when it is consumed affect whether the nutrients are taken up by active tissue (muscles, brain, heart, etc.) or stored as triglycerides in the adipose (fat) tissue. One of the most important hormones is insulin. It is a storage hormone, signaling the uptake of glucose and fatty acids to be stored. Insulin is opposed by a variety of hormones, including glucagon and epinephrine. A diet high in carbohydrates, will raise insulin levels, thus stimulating adipose tissue to take up glucose and fatty acids from the blood. Vital organs will experience a state of semi-starvation. Consuming a diet rich in refined sugars leads to the ironic condition of malnourished obese individuals, who have high levels of circulating insulin. With weight loss or a carbohydrate-restricted diet insulin levels will go back down to normal levels.
I hope you can appreciate that the body is a very sophisticated organism that has functioned amazingly well for thousands of years. Now, too many Americans are over fat. Applying a simple equation (law of energy conservation, energy is neither created or destroyed) developed in the 19th-century from steam engine design has consistently failed to help us improve our body fat levels. Unfortunately, lots of medical, health and fitness experts will continue to recommend restricting Calories and simply expending more. Until they finally realize that they are viewing the root of the problem (obesity) wrongly, Americans will continue to struggle with obesity and its complications. We need to view it as a metabolic malfunction based on the modern diet (high consumption of refined carbohydrates) and the modern environment (lack of the appropriate hormonal signals to build muscle and keep burning fat naturally, such as regular, natural spikes in growth hormone and testosterone in response to resistance training and high intensity exercise). Fortunately, some of you are getting the results you want with the right information.