Losing Weight and Immune System

Written by: Alojz Ihan, M.D., Ph.D.

Dieting causes the same response of immune system as really strong stress. Why is it so?

When dieting, our organism reacts to lack of sugar by starting the production of stress hormones to decompose fats. These decomposed fats are then transported by our blood to liver, where they are broken down into glucose. So actually the stress hormones cause weight loss. Everything sounds great so far. But unfortunately stress hormones are also decelerating the immune system.

This unfortunate double role of the stress hormones make every weight-loss tightly connected to slowing down our immune system. Thus we are overwhelmed with hormones when losing weight, especially if we do it intensively. These hormones strongly weaken our immune system (actually, such hormones are used after transplants when we need to restrict functioning of the immune system so that the body doesn't fight against new organs).

Dieting brings another threat for our immune system – our immune cells are deprived from getting essential nutrients, especially proteins, vitamins, and minerals, needed for efficient response of our immune system.

Especially harmful can be extreme dieting by only eating one type of foods (e. g. only meat and eggs), because we do not provide all essential nutrients for our immune system.

Thus it is very important to keep a balanced diet with proper calorie intake limit when losing weight. Besides that it is good to consume some vitamin and mineral supplements.

Losing Weight Affects Our Immune System in 2 Ways

On one hand stress hormones are overwhelming our body and are slowing down our immune system, on the other inappropriate diet can harm our immune system additionally because of lack of suitable proteins, vitamins, and minerals, essential for proper immune response.

One way or another, we have to keep in mind that after a distinct weight-loss our body needs more time to recover. If we lose one fifth of our weight, we can expect our immune system to work as before the weight loss a year after we finish our diet.

In the mean time we have to avoid possible infections (taking care of our teeth, pay attention to our wounds, to stay in bed when having a cold). Especially few weeks or months after the end of dieting, when organism is not under stress anymore, we are very sensitive to severe, even deadly infections.

We have to avoid everything that could weaken our immune system: stressors, severe physical strain, heavy emotional burdens, sleepless nights, severe cold.

Adding a distinct physical strain on the pile weakens immune system even more. Doctors from the US army published a study in 2011, which reports that a combination of strenuous training and dieting (losing about 15 to 20 percent of body weight) noticeably weakened normal immune parameters and strongly increased susceptibility to virus infections. So it is not appropriate to run marathons or perform other exhausting activities when losing weight.

It is also clear from all that's written above, that we destroy our immune system with a diet; we soon get the lost weight back and then repeat the whole process again and again … and again. But from our immune system's point of view it is not recommended to have more than one intensive diet a year.

If we get the lost weight back after the diet, we should wait. Not only because of the immune system, but also to think about the real reason for our excessive weight and what to do about it to make the next weight loss long term. Probably, it is better to accept the existing condition; it's better to have some unpleasant fatty tissue than a broken immune system followed by numerous diseases.