Why does constipation occur when losing weight? What are the reasons

constipation during weight loss may be related to changes in dietary structure, insufficient water intake, imbalanced gut microbiota, reduced exercise, increased mental stress, and other factors. If there is a sudden reduction in food intake or a change in dietary structure during the weight loss process, it may lead to a slowdown in gastrointestinal motility, which in turn can cause constipation symptoms.

1. Changes in dietary structure

During weight loss, excessive reduction of staple foods or fat intake can lead to insufficient dietary fiber. Dietary fiber can absorb water, increase fecal volume, and stimulate intestinal peristalsis. Suddenly reducing the intake of high fiber foods such as whole grains, legumes, vegetables, and fruits may cause dry stool. It is recommended to gradually adjust the diet structure, ensuring a daily intake of 300-500 grams of vegetables and 200-350 grams of fruits, and choosing coarse grains such as oats and brown rice instead of refined rice and flour.

2. Insufficient water intake

Some weight loss individuals intentionally reduce water intake to avoid edema, but insufficient water intake can cause the colon to excessively absorb water from feces. Adults should drink 1500-1700 milliliters of water per day, and increase to 2000 milliliters in sports or high temperature environments. Drinking 300ml of warm water on an empty stomach in the morning can stimulate the gastrocolic reflex, and drinking water half an hour before meals can enhance satiety and improve intestinal lubrication.

3. Imbalance of gut microbiota

Rapid weight loss may disrupt the balance of gut microbiota, and a decrease in beneficial bacteria such as bifidobacteria can affect the production of short chain fatty acids. Short chain fatty acids can provide energy to the intestinal epithelium and promote peristalsis. Moderate consumption of sugar free yogurt, kimchi, and other fermented foods is recommended. If necessary, probiotic preparations such as Bifidobacterium triple viable capsules can be used under the guidance of a doctor.

4. Decreased Exercise

Some weight loss individuals reduce their physical activity due to dieting, but lack of exercise can weaken the tension of abdominal and intestinal smooth muscles. It is recommended to engage in 30 minutes of aerobic exercise such as brisk walking and swimming every day, combined with core training such as supine abdominal exercises. Taking a 15-20 minute walk after meals can utilize the gastrocolic reflex to promote bowel movements.

5. Increased mental stress

Strict calorie control may activate the hypothalamic pituitary adrenal axis, and elevated cortisol may inhibit intestinal peristalsis. Anxiety can also cause tension in the pelvic floor muscles, affecting the defecation reflex. Stress can be relieved through meditation and abdominal breathing, and if necessary, consult a psychologist. Maintaining 7-8 hours of sleep helps regulate the autonomic nervous system.

During weight loss, it is recommended to use a gradual calorie deficit, reducing 300-500 calories per day to avoid completely cutting off carbohydrates or fat. Diet and bowel movements can be recorded. If constipation persists for more than 3 days or is accompanied by abdominal pain or bloody stools, medical attention should be sought. Appropriately increasing foods rich in unsaturated fatty acids such as walnuts and flaxseeds can enhance satiety and lubricate the intestines. Develop a fixed defecation habit, such as trying to defecate 30 minutes after waking up in the morning or after a meal, and maintaining a squatting position during defecation is more ergonomic.