Most want to lose weight — but not you?

What causes underweight?

While many people struggle to shed extra kilos, others need to gain weight for various reasons. A deliberate and balanced weight gain can have a positive impact on health and well‑being. 

There are several reasons someone may need to gain weight. People who are underweight may need to increase their weight due to genetic factors, metabolic disorders, insufficient food intake or illnesses. Being underweight negatively affects health because it weakens the immune system, increases the risk of malnutrition and leads to an energy deficit. 

After an illness or surgery, weight loss can occur, which can weaken the body and impair recovery.

To restore health and strengthen the body, adequate nutrient intake and weight gain are necessary. People with eating disorders such as anorexia or bulimia often need to gain weight as part of their recovery. Eating disorders can cause significant weight loss and nutritional deficiencies, which can be life‑threatening. In these cases, weight gain is managed by professionals to ensure it is healthy and controlled. 

Certain hormonal disorders can lead to weight loss because they affect metabolism and appetite. Weight gain in these cases often requires a combination of medical treatment and dietary changes to provide the body with necessary nutrients and increase weight in a controlled way. Some people aim to gain weight to improve their overall well‑being. They may feel underweight, lack energy and strength, or simply want to feel healthier.

How is underweight defined?

Underweight is defined as a Body Mass Index (BMI) under 18.5 in adults. BMI is a measure that indicates the relationship between a person's body weight and height. 

BMI is only a rough guideline and should not be used alone to assess health. For particularly tall or short people (under 1.55 m or over 1.90 m), BMI may be less informative. 

What are the consequences of being underweight?

The effects of being underweight can affect the whole body. Underweight people often feel quickly tired, run down and lacking drive. Muscle strength declines and breathlessness occurs sooner. The risk of infection is increased because the immune system is weakened. Wound healing may also be impaired. 

Concentration and memory decline. In women, severe underweight disrupts the menstrual cycle and affects fertility. Long‑term underweight also increases the risk of brittle bones (osteoporosis) and can damage organs such as the heart, liver or kidneys. 

For athletes, fitness enthusiasts or people who want to improve their body composition, building muscle is often a main goal. Building muscle mass leads to weight gain because muscle tissue is heavier than fat tissue. After an illness or surgery, weight loss can occur and weaken the body, impeding recovery.

What role does nutrition play in healthy weight gain?

Healthy weight gain does not mean loading up on unhealthy, calorie‑dense junk food. It is about a balanced diet that is rich in nutrients and provides the body with the required calories. 

The key to gaining weight is a calorie surplus. This means you need to consume more calories than you burn. A surplus of about 500 calories per day can lead to a healthy weight gain of around 0.5 kg per week. It is important that these extra calories come from healthy sources and not just junk food. 

A good way to gain weight healthily is to focus on calorie‑dense but healthy foods that contain the necessary nutrients. These include foods such as nuts, seeds, avocados, oily fish, whole grains, legumes and healthy oils. These foods provide a good amount of calories while also offering important nutrients like protein, healthy fats, vitamins and minerals. 

In addition, make sure to plan meals and eat regularly. Instead of only three main meals a day, snacks between meals can help increase calorie and nutrient intake. Snacks include yoghurt, nuts, dried fruit, cheese or protein‑rich smoothies. Proteins are important for building muscle mass. Protein‑rich foods such as chicken, fish, eggs, beans, lentils, dairy and nuts should be included in the diet. Protein not only supports muscle growth but also the repair and renewal of body tissues. For healthy weight gain, about 1.5 to 2.2 grams of protein per kilogram of body weight per day is recommended. A protein‑rich diet supports muscle growth and helps avoid unwanted fat gain. 

Instead of simple carbohydrates like sugar and white flour products, opt for complex carbohydrates such as whole grains, oats, quinoa and brown rice. Complex carbs provide sustained energy and help the body make efficient use of extra calories. 

Alongside nutrition, regular resistance training is crucial for building muscle mass. Resistance training not only promotes weight gain but also improves body composition and strength.

How can you gain weight in a targeted and healthy way?

• Increase your daily calorie intake moderately to encourage healthy weight gain.
• Ensure the extra calories come from nutrient‑rich foods that provide important vitamins, minerals and fibre.
• Spread your meals over five to six smaller meals throughout the day to meet your calorie needs more effectively.
• Although vegetables are low in calories, they contain many important vitamins and minerals. Add vegetables to your meals to increase nutritional value.
• Avoid foods with empty calories such as sugary snacks and drinks, as they provide little nutritional benefit.
• Small bitter starters like arugula, chicory or herbs such as basil, thyme or rosemary can stimulate digestive juices and appetite.
• Track your meals and snacks to keep an overview of your calorie intake and ensure you eat a balanced diet.
• Plan meals and snacks in advance to ensure you have balanced, calorie‑dense options available.
• Supplement your fluids with calorie‑rich drinks like milkshakes, smoothies, fruit juices or protein shakes.
• Drink enough water to keep your body hydrated. This is important for healthy digestion and metabolism.
• The right training is essential to build not only fat but also muscle. Focus on resistance training. It is advisable to lift weights two to four times per week.
• In resistance training, focus on fewer repetitions with heavier weights. Choose weights that allow you to perform 6 to 10 repetitions per set. Do three sets per exercise.
• A small protein‑rich meal before bed helps minimise muscle breakdown during sleep and supports weight gain.
• A meal or snack after training that contains carbohydrates and protein supports muscle recovery and aids weight gain.
• Stress can reduce appetite and lead to weight loss. Find ways to reduce stress, such as meditation, yoga or walks in nature.
• Weight gain takes time and patience. Be patient with yourself and trust the process. Slow and sustainable weight gain is healthier and easier to maintain than rapid, unhealthy increases.
• If you have personal questions or concerns, it is advisable to consult a doctor or dietitian for tailored support.

Healthy weight gain requires a balanced diet, regular exercise and stress reduction. By combining these factors you can reach your goals and promote long‑term, sustainable weight gain.