The hormone cortisol is released in greater quantities in the body during periods of upset or stress. Too low a quantity may seriously impair our reactions in hazardous situations. Too high a quantity of cortisol results in consistently high levels of blood sugar, obesity and susceptibility to infections.

Melatonin is responsible for coordinating the biorhythms of the body and acts as a timer for the circadian (daily) rhythm. During the night, the concentration of melatonin increases ten-fold and, in turn, leads to the release of growth hormone and stimulation of the immune system. Aside from influencing the immune system, increased or decreased levels of melatonin can cause sleep disorders. Chronic disruptions to the melatonin rhythm also result in weight gain.

The "happiness hormone" serotonin has a number of effects on our emotions, particularly with a view to depression, panic attacks, headaches, eating habits (sweet cravings) and dealing with stress. Serotonin deficiency can cause sleep disorders and pathological muscle tension (known as fibromyalgia).

Insulin is an important hormone for regulating the digestion, our feeling of fullness and blood sugar levels. Leptin regulates, among other things, our feelings of hunger and serves as an indicator for hidden fat reserves in the body. Measurement of leptin even enables the most hidden of fat depots to be detected (keyword TOFI: thin on the outside fat on the inside).

The thyroid hormones help to maintain a stable energy balance in the organism and have a tremendous influence on many of the hormone-producing organs. Symptoms of an overactive thyroid may be palpitations, high blood pressure, restlessness, weight loss, increased sweating, diarrhoea, hair loss, irritability, depressive moods and sleeplessness. An underactive thyroid causes potential symptoms such as diminished physical fitness, weakness, a lack of drive, slack skin, swollen lids, fatigue, sensitivity to the cold, cold extremities, depression, chronic constipation, weight gain and loss of appetite.

Various releasing hormones ensure that the hormones in the blood are transported to the correct organs.