Exercise Weight Loss Biology

If you’re interested in maximizing your weight loss, you need a thorough understanding of the biology of exercise and weight loss. Although every body works differently, all bodies abide by the same biological rules and processes that lead to weight gain or weight loss.

These rules also influence how exercise helps us build the kinds of muscle and fat we need to stay healthy. Learn about the biology of exercise and weight loss, and how your body processes what you put in it.

What Causes Weight Loss

Your body constantly burns calories (even as you eat) to keep you functioning–your blood flowing, eyes blinking and organs working–so you need sufficient calories every day: typically between 1,500 and 2,000 for the average adult. The following are two ways to determine how many calories your body needs per day.

You can calculate these on your own with complex mathematical formulas or, better yet, consult an exercise physiologist or dietitian for help in doing so:

  • Basal metabolic rate (BMR) determines how many calories you need to perform basic bodily functions like respiration and breathing.
  • Resting metabolic rate (RMR) indicates the number of calories your body expends in a resting state.

These metabolic rates, in addition to other factors, such as physical activity, gender, weight and genetics, all play a part in weight loss. When a negative balance–or a deficit–exists between your metabolic rate and the calories you use, weight loss will result.

Exercise Stimulates Caloric Burn

Increasing physical activity can increase weight loss, especially when you burn more calories than you consume, creating a negative balance. In the biology of exercise and weight loss, the calorie is simply a measurement of the energy required to raise the temperature of one gram of water by one degree Celsius.

Just like the calorie is a simple measurement of energy, weight loss is a straightforward equation that involves calories eaten and calories used. Depending on the kind of physical activity you choose, you may significantly increase the number of calories burned each day.

The Right Kinds of Muscle and Fat

Did you know that your body needs (yes, “needs”) fats, for healthy skin, hair and brain health? Monounsaturated fats (MUFAs) support weight loss and cardiovascular health, and are found in olives, nuts and avocadoes. The more muscle your body builds, the more fat that you’ll burn naturally and efficiently.

Note that this increase in muscle may lead to an increase in body weight, since muscle is denser than fat. Exercise builds the right kinds of muscle and uses our body fat as an energy source for our muscles. Once your body efficiently converts this stored energy, you may start to notice weight loss, changes in your appearance and an improvement in overall bodily health.


Bramble, L. (n.d). Monounsaturated fats