How Your Brain Controls Your Weight

In this article we will review how your body uses energy from food. We will see how your body tries to maintain a set weight and how chemical signals to your brain make it difficult, but not impossible, to maintain long-term weight loss.

The amount of energy that your body uses every day is called your total daily energy expenditure (TDEE). The components of your total daily energy expenditure include:

your basal metabolic rate (BMR) which accounts for 60 to 80% of the calories that you burn every day
the thermic effect of food (TEF) which is the energy that your body uses to digest and absorb fat, carbohydrates and proteins that you eat
Exercise activity thermogenesis (EAT) which is the energy used during exercise
Non-exercise activity thermogenesis (NEAT), which measures the amount of energy that you use while engaged in activities other than exercise such as fidgeting, walking around the house or standing in line at the store.

It is usually difficult to maintain weight loss because your body will try to maintain your typical weight. After weight loss, several things occur in the body that make it more difficult to further limit food intake and to burn additional calories with exercise. When you lose fat cells, the level of leptin in your blood decreases (leptin is produced by your fat cells). The low leptin level makes your brain think that you are low in stored energy and that you are below your natural weight.

Thus, your brain will then tell your cells to save energy instead of wasting it. You will burn fewer calories when you are exercising and your basal metabolic rate will decrease. Your body will use energy more efficiently in almost every physical task meaning that you will waste less energy as heat. Because your body is trying to save energy, you will want to eat more as well.

The bottom line is that your brain controls your body’s energy balance. Hormones released by your fat cells, pancreas, stomach and gut act on your hypothalamus and other brain centers to communicate the status of your current energy balance. These hormones, including leptin, insulin and ghrelin, will try to maintain homeostasis in your body, meaning that your body will try to maintain your previous weight after recent weight loss.

Most people who successfully maintain long-term weight loss exercise regularly. Physical exercise strains your muscle, creates temporary inflammation and forces muscle to rebuild so that is stronger. Researchers have discovered a hormetic effect of exercise, meaning that a low amount of stress actually benefits your muscle and decreases inflammation in the long term. Recall that inflamed fat is the real culprit behind obesity-related disease.

In addition, regular exercise fine-tunes your body and allows energy and oxygen to get to the cells that need it more quickly and efficiently. Exercising muscle needs more oxygen which is carried by the blood to your muscle cells. So new blood vessels are formed in muscle and fat tissue with regular exercise. This increases oxygen supply to fat cells, making it less likely that fat cells will die due to lack of oxygen. Dead fat cells are attacked by immune cells and increase inflammation levels in your body.

Physical activity also strengthens your blood vessels, helping them transport blood and oxygen more effectively.

Monitoring your weight on a regular basis is the most effective way to track progress in weight loss. Counting calories is not very accurate considering that federal law allows a margin of error of up to 20% in calorie counts that are reported on nutritional labels. It is also challenging to accurately count the number of calories burned during exercise, especially on an individual level. Depending on the current energy balance in your body and whether or not you are dieting, your cells may be trying to save or waste calories. Consequently, the number of calories burned during exercise will vary with the individual.

You burn most of your calories just by staying alive- your body needs a large amount of energy to provide fuel to your organs, to maintain your body fluid levels in the right concentrations and to just keep your body in working order. This is the energy consumed by your basal metabolic rate.

In summary it is often difficult but definitely not impossible to maintain weight loss over time. This is because hormones such as leptin will act on the hypothalamus in your brain to conserve energy if your brain perceives that you are below your natural or typical weight.

You are more likely to achieve long-term weight loss and prevent diabetes by avoiding processed foods with added sugar as these foods will release too much glucose into your blood too quickly. By eating natural and unprocessed foods you will make it easier for your body to process glucose as there will be less of it entering your blood. If you consume a lot of processed food your body will be unable to process all the glucose and it will be stored as fat.

As you gain more and more fat cells, your insulin and leptin levels will increase, making it more likely that you will develop insulin resistance and leptin resistance. If you accumulate too many fat cells it also becomes more likely that these cells will get too big and die. When fat cells die, specialized immune cells called macrophages will suck them up and release attack chemicals such as interleukin 6 (IL-6) which will first cause inflammation in the fat cells and then in the rest of the body. Inflammation is what makes obesity so deadly.