What Happens to the Body When we Diet?

By Sally Robertson, B.Sc.Reviewed by Afsaneh Khetrapal, BSc

The body starts to respond to healthy dietary changes as soon as they are made. This can be advantageous, because a diet can then eventually reduce the risk of obesity, diabetes and heart disease, as well as improve a person’s overall sense of well-being.

Control of blood glucose level

Eating carbohydrates increases the blood sugar level, but the extent of this rise depends on a food’s glycemic index. The glycemic index is a ranking system, based on a score of 1 to 100, that determines the effect of a food on blood sugar levels.

Foods with a high glycemic index are quickly broken down, leading to sharp increases in blood sugar, followed by sharp drops. Sharp fluctuations in the blood sugar level can increase the risk of diabetes, obesity and heart disease. It follows that avoiding such foods with a high glycemic index such as soft drinks, candy and white bread can lower these risks.

Ensuring a steady blood sugar level by opting for foods with a low glycemic index sustains the body’s energy levels. The sharp spike in blood sugar and sharp drop that follows is avoided and energy levels are sustained. A steady level of blood glucose can also prove beneficial, since a lowered blood sugar, which is common after a spike, can disrupt the ability to concentrate and learn.

Coffee and cortisol

Cutting down on coffee can reduce the level of the “stress hormone” cortisol in the body. A high cortisol level can decrease a person’s ability to manage pressure and can also be damaging to the immune system. Caffeine increases these adverse effects of the hormone and reducing coffee intake can immediately help to limit the adverse effects of cortisol.

Severe calorie restriction

Sever calorie restriction impedes weight loss rather than aiding it, since it prevents the body from burning fat effectively. The body behaves as if it is being starved, as a defence mechanism, and becomes highly efficient at using the energy available to it. It starts to protect any stores of fat and derives energy from muscle and lean tissue instead. This results in muscle loss and, therefore, a lower metabolism, so that fewer calories are needed. This lowered metabolism, in turn, slows weight loss down.

The metabolic rate is affected by the degree of muscle mass - the metabolic rate is higher in those with more muscle mass. Muscle burns many more calories than fat does and losing muscle therefore reduces the metabolic rate and the number of calories burned.

It is important that people maintain a healthy metabolic rate, particularly when they are dieting, and this requires them to both diet and exercise sensibly. Strength-enhancing exercises are particularly effective at increasing muscle mass. For every additional pound of muscle a person develops, the body burns up approximately 50 more calories every day.

To avoid an unhealthy drop in the metabolic rate, experts generally recommend calorie intake is never restricted to less than 1,000 to 1,200 calories per day.

Further Reading

• All Diet Content
• Low Calorie and Very Low Calorie Diets
• Diabetic Diet
• DASH Diet for High Blood Pressure
• High Protein Diet