In relation to food and the body, calories are units of energy that allow the body to work. Food provides this energy, some of which the body stores and some of which it uses. As the body breaks down food, it releases calories as energy.
Max Wishnofsky first propagated the concept that there are approximately 3,500 calories in a pound (lb) of body fat.
Put simply, to lose 1 lb of body fat per week, people will need to have a deficit of around 500 calories per day. They can achieve this by consuming roughly 500 calories fewer than they are currently, by burning an extra 500 calories per day with exercise, or a combination of the two.
If the body takes in too many calories or burns too few, weight gain occurs. This is because the body stores calories it does not use as body fat. Organs including the brain, heart, lungs, liver, and kidneys account for roughly 80% of total daily energy use.
Recent research calls this rule into question, concluding that it overestimates someone’s weight loss potential. The rule does not take into account dynamic changes in metabolism, hunger, and satiety levels as weight loss occurs.
The National Institutes of Health (NIH) have developed a new, more accurate rule-of-thumb: Every 10 calorie decrease per day leads to an eventual 1 lb loss. Only time will tell how long that weight loss takes, so patience and consistency is key.
How fat works
Body fat, or adipose tissue, consists of adipocytes.
These are fat cells, and they occur alongside other types of cells and proteins. Fat cells contain lipids, including cholesterol and triglycerides.
Adipose tissue stores energy for the body to use and protects the organs. It also releases hormones that control many functions in the body, such asinsulin sensitivity and appetite.
People with more body fat may experience something called leptin resistance, in which the body is less sensitive to the satiety hormone leptin. This, in turn, drives up hunger and food intake, making weight maintenance harder over time.
There are two types of adipose tissue: white and brown. Brown adipose tissue is more metabolically active. It burns more calories and helps manage weight, insulin sensitivity, and overall health to a greater extent than white adipose tissue.
If people have excess body fat, it is most often due to the fact that their white adipose tissue has expanded.
Having too much body fat can cause obesity and result in many health problems, including diabetes, high blood pressure, and heart disease. Having too little body fat can also be harmful and lead to health concerns such as malnutrition and fertility issues.
How calories work
Research estimates that muscle burns calories at a rate of 10–15 calories per kilogram (kcal/kg) per day. This amounts to 4.5–7 kcal/lb per day.
Muscle accounts for roughly 20% of total energy expenditure each day. For people with 20% body fat, body fat accounts for 5% energy expenditure.
So, people with more muscle tissue have a higher metabolic rate. This means that they burn more calories and are able to maintain their body weightmore easily.
Culled from Medical News Today
