Low energy availability and gastrointestinal symptoms
Problems with digestion?

The health of the body can be represented as a continuum, as a spring of a certain alpine river where the water coming from the rocks is pure or in the case of a human all body functions are working optimally. As we move along the river, the function of the organs declines, more diseases appear, the metabolic flexibility decreases and so on and on. The function of the organs and the organism is very much dependent on the availability of nutrients and energy. An insufficient intake of macro- and micronutrients, a calorie restriction or even caloric surplus, can negatively influence the function and shift health to the undesirable side of the continuum.

Calorie restriction can be a consequence of an intentional diet or unintentional malnutrition. We introduce diets into our lifestyle to improve body composition, lose weight, improve body function and metabolic flexibility. However, a long-term calorie restriction and the resulting low energy availability can severely affect body functions. Recently defined term Relative Energy Deficiency in sport (REDs) summarises all the characteristics and consequences of low energy availability. It has been adapted from the term Female Athlete Triad, which linked low energy availability, menstrual cycle dysfunction and low bone mineral density. Since low energy availability affects not only female but also male athletes, it makes ”REDs” a more appropriate term. In addition, low energy availability affects not only the reproductive system and bone health but also other physiological systems such as metabolism, the immune system, the cardiovascular system and also mental health, so basically the whole person.

Real cases of REDs

Recently I was contacted by a number of clients who were suffering from REDs and thus the absence of menstruation. These clients had digestive problems, reported flatulence and poor digestion; which affected some food groups as if they were intolerant to those. On the advice of some nutritionists or Dr Google, they thought that detoxification and elimination diets could solve their problem. But here is the catch. The implementation of detoxification diets, the elimination of major food groups and fasting only further promote low energy availability. Since people with REDs generally already follow a very healthy diet, high fibre intake can cause various gastrointestinal problems such as flatulence and constipation.


In a study conducted by Scandinavian scientists, female athletes with low energy availability reported a higher degree of gastrointestinal symptoms. An energy insufficiency can lead to a reduction of the mucosal tissue in the intestine, which could partly explain the problems. In line with this, a study of female bodybuilders who observed the symptoms of REDs came to similar conclusions. RED symptoms, including gastrointestinal problems, were assessed both in the week before the competition and after the competition. Before the competition, slimmer athletes showed more symptoms of eating disorders and REDs. Their resting metabolic rate decreased as well as their resting heart rate, but they reported significantly more gastrointestinal symptoms. After resuming a normal diet after the competition, the symptoms seemed to become less severe. Importantly, many female bodybuilders reported menstrual disorders, both in the past and just before the competition. Despite normalisation of the diet and weight gain after the competition for one month, the problems of menstrual disorders were not solved. Most likely, the post-competition recovery period was not long enough because the hormone system may need more time to recover.

According to the studies mentioned, gastrointestinal symptoms such as flatulence, diarrhoea, cramps, constipation, etc. can be associated with low energy availability and diet. Increased energy intake could help to alleviate gastrointestinal symptoms in athletes suffering from these symptoms and REDs. However, it should not be forgotten that excessive physical exercise can also contribute to gastrointestinal disorders.

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