Intermittent Fasting and Hormones: Benefit or Harm

Intermittent fasting has gained significant popularity in recent years among those looking to improve their health or lose excess weight. This eating system involves alternating periods of eating with periods of fasting. The most common regimes include 16/8 (16 hours of fasting and 8 hours for eating) or 5/2 (5 days of regular eating and 2 days of restricted calorie intake).

However, the question of how intermittent fasting affects hormonal balance is of great interest. Hormones are key regulators that influence appetite, metabolism, energy levels, and even mood. Let's explore what hormonal changes occur in the body during intermittent fasting and whether it is beneficial for health.

How intermittent fasting affects hormones

1. Insulin and its sensitivity

Insulin is a hormone that regulates blood glucose levels. When we eat, insulin levels rise to help the body store glucose for future needs. During fasting, insulin levels naturally decrease, allowing the body to use fat stores as an energy source.

Studies have shown that intermittent fasting can increase the sensitivity of cells to insulin, which is an important factor in preventing conditions such as metabolic syndrome and type 2 diabetes. However, people with existing blood sugar level disorders (such as hypoglycaemia) should consult a doctor before starting the practice.

2. Cortisol – the stress hormone

During prolonged fasting, cortisol levels may rise. This hormone stimulates the release of glucose from the liver, providing the body with energy in conditions of food scarcity.

However, constantly elevated cortisol levels can have negative consequences, including impaired sleep quality, anxiety, and the risk of developing chronic diseases. Therefore, it is important to avoid excessive stress and choose a fasting regime that does not cause physical or psychological discomfort.

3. Growth hormone (HGH)

Growth hormone is one of the most important regulators of metabolism and tissue regeneration. During fasting periods, the level of this hormone can increase significantly – sometimes by up to 5 times.

The increase in growth hormone promotes fat burning, muscle mass preservation, and cell regeneration. This is one of the reasons why intermittent fasting has become popular among athletes and those looking to improve their physical fitness.

4. Leptin and ghrelin – hunger and satiety hormones

Leptin is a hormone that signals the brain about satiety, while ghrelin, on the contrary, stimulates appetite. Research suggests that short-term fasting can lower leptin levels and increase ghrelin levels.

This mechanism explains why many people experience strong hunger at the beginning of intermittent fasting. But over time, the body adapts, and the hormonal balance stabilises, allowing better appetite control.

Benefits of intermittent fasting for hormonal health

Improved metabolism. By lowering insulin levels and increasing growth hormone, intermittent fasting promotes active fat burning.
Appetite control. Over time, the balance of leptin and ghrelin helps reduce overeating.
Reduced risk of chronic diseases. Regulating insulin levels and reducing inflammatory processes can lower the risk of developing diabetes, cardiovascular diseases, and obesity.
Improved brain function. Fasting stimulates the production of brain-derived neurotrophic factor (BDNF), which supports neuron health and improves memory.

Potential harm of intermittent fasting

Despite numerous benefits, intermittent fasting is not suitable for everyone. Some people may experience the following side effects:

Hormonal imbalance in women. Excessive fasting can negatively affect the production of oestrogen and progesterone, which may lead to menstrual cycle disruptions.
Increased stress. Elevated cortisol levels can cause emotional fluctuations and anxiety.
Sleep disturbances. For some people, evening fasting can make it difficult to fall asleep.
Risk for those with certain diseases. For example, intermittent fasting may be dangerous for people with type 1 diabetes, chronic gastrointestinal diseases, or eating disorders.

How to make intermittent fasting safe

Consult a doctor. Before changing your eating regime, it is advisable to consult a specialist, especially if you have chronic diseases.
Choose a suitable regime. Start with milder options, such as 12/12 (12 hours of fasting and 12 hours of eating), to give your body time to adapt.
Listen to your body. If you experience significant discomfort, try reducing the duration of fasting or return to your regular eating schedule.
Focus on the quality of food. During eating periods, prioritise a balanced diet rich in proteins, healthy fats, and complex carbohydrates.

Remember that every body is unique, so it's important to consult with specialists before starting intermittent fasting. At the Bezugla Clinic Centre for Clinical Dietetics specialists will help you choose the optimal eating regimen that suits your needs and does not harm your health.

This article is educational and does not replace individual medical consultation.

Intermittent fasting and hormones: benefit or harm