Eat healthy meals
You should eat nuts, fruits and use lots of olive oil while cooking. Find foods that contain large amounts of healthy, unsaturated fats. These are high in calories and are less likely to damage cardiovascular health or form into unhealthy fat deposits. Seek out milk or milk products in things you eat, or you may have problem gaining weight, as lactose intolerance mostly causes digestive hardships even when only small amounts of dairy are present, destroying weight gain efforts. Also, do not eat a lot of junk food such as chips, sugary food and sweetened baked goods. Junk food can increase body weight for a little while, but in underweight people, it’s mass that normally does not stick with the body for a longer time period. It can give you a jiggly gut that evaporates as quickly as it came on.
Prefer muscle mass to fat
You need to concentrate your efforts on building muscle mass rather than building up fat. Increasing caloric intake will quite often increase the body’s fat levels. Therefore, as long as you are taking protein from healthy sources such as fish, lean meat, eggs, chicken, nuts and protein powder supplements, muscle growth will happen if you exercise on a regular basis. Moreover, try to maintain increased caloric intake balanced with regular physical exercise. Exercise will not go against weight gain efforts so long as you consume more calories than you burn when you work out. A great food option for lactose intolerant people that want to gain weight are those extracted from soy. Soy milk is highly rich in protein and high in calories. It also contains no lactose so it is safe as well.
You can have calcium supplements to make up for not consuming any dairy products. Calcium enriched orange juice is a good option in place of nutritional supplements, or nutritionally enriched cereal with soy milk. To add more calories without turning to lactose consisting sauces or condiments, eat fatty but healthy products such as peanut butter or avocado.