We can make simple distinction for human body composition type: 1. Ectomorph - naturally skinny and hard to gaining weight. 2. Mesomorph - easy to get weight also easy to lose weight. 3. Endomorph - naturally heavy and easy gaining weight (usually fat) and hard to losing it. If you ectomorph, its mean you need enough calories to get lean mass. What to do is eat more. If you eat more calories than you burn, you will not lose your weight. Simple calculation to determine calori intake is multiply your body weight by 15,example 150 pound person need to consume 2250 calories a day. Next is diet strategy for more calories. 1. Consume lean protein, such as chicken (no skin include) , beef (no fat), egg whites, fish. 2. Consume unprocessed carbohidrat, oatmeal, sweet potatoes, rice, cereal, bread. 3. Fruit and Vegetables, contain vit, mineral and many nutrients good for growth. 4. Good Fat, almond, peanuts, avocado, olive oil 5. Eat more frequently with small size, don't eat big portion th