## Genetics or disease First, it is important to understand the reason for being underweight. In a macro sense, there are two likely reasons: genetic body type or health problems. It can be assumed that you belong to the first category if you have been thin throughout your whole life and have family members who are thin. There should be cause for alarm if there is sudden and noticeable weight loss accompanied by unhealthy symptoms such as general weakness, stool disorders, bad moods, dry skin and mucous membranes, brittle hair and nails, hair loss, dizziness, menstrual cycle disorders, or decreased libido. ## Start with a checkup There are a number of illnesses that are characterized by weight deficiency. These include endocrine diseases, gastrointestinal problems, nervous and mental disorders, and cancer. In order to rule them out, it's worth taking a basic checkup before experimenting with ways to gain weight, even if you have no obvious health problems. It includes=== : - General blood and urine test - Blood glucose test - Biochemical blood test with determination of thyroid hormones, total protein and protein fractions, immunoglobulins, total lipids, cholesterol, potassium, calcium, sodium, iron, and its fractions - General stool analysis and stool test - Ultrasound of abdominal organs and ECG - Gastroscopy and colonoscopy for gastrointestinal problems A person being underweight or overweight is often judged by the body mass index: BMI = (weight in pounds x 703) / (height in inches x height in inches). However, this formula is incorrect because it does not take into account body composition including muscle and bone mass, fat and fluid distribution as well as sex, age, and body shape. These parameters will be shown by a hardware bioimpedance analysis, which is based on anthropometric data and electrical resistance values of tissues. The analysis will make it possible to understand what makes it possible to gain weight — fat or muscle mass. ## If your health is good If this is the case, then you can seriously address the problem. To begin, as in the case of weight loss, you will have to change your lifestyle. The main principle of weight gain is to consume more calories than your body burns. Based on bioimpedance analysis, a nutritionist will calculate how many calories you spend on your metabolism to maintain vitality, then multiply by the activity ratio and add an additional 500-700 kilocalories. > Experts at the U.S. Department of Agriculture have calculated that in order to gain 1 pound per week, you need to consume about 500 extra kilocalories per day. You should eat five meals a day. Your diet should include complex carbohydrates (pasta, cereals), healthy fats (avocados, fatty fish, oils, high-fat dairy products), and proteins (eggs, beans, milk, poultry). The percentages are 20 % protein, 20-30 % fat, and the rest are carbohydrates. Spices and seasonings in dishes will increase appetite. Gaining weight can also be achieved through muscle mass. This requires a sports load with an emphasis on strength training three times a week. Make sure you tell your trainer about your goals so that he or she can select the right program. You can increase the amount of protein in your diet with protein shakes on the days of training. Also, you should control your sleep regime and stress resistance. ## What you should not do - Eat too much, which can lead to problems with the gastrointestinal tract. - Eat only fatty and sugary foods, which can help with weight gain but undermines health. - Independently prescribe yourself drugs and dietary supplements that increase appetite. - Do too little or too much physical activity. ## Is it useful to be thin? Everything is good in moderation. People with a normal BMI have a greater chance of a long and healthy life than those who are overweight or overly thin. Being underweight weakens the immune system and can cause vitamin deficiency, anemia, muscle and bone atrophy, osteoporosis, infertility, kidney disease, and more. So, even if you like your appearance, it doesn't hurt to put on a few pounds.