Sometimes very active people have problems with maintaining their body weight or gaining weight while juggling an active training program. Unfortunately, no food in particular will help to speed up or slow the metabolism, but timing and spacing of meals can help. It is actually quite difficult to gain weight when one is trying consciously to do so.
In order to gain weight, the calories you take in must be more than the calories you burn. Of course, it is important to be sure you take in the right calories to enable healthy muscle weight gain and minimize fat gain. One of the most common misconceptions with athletes is that protein is the only thing needed for weight gain and muscle growth. It is a little more detailed than that. Calories, carbs and protein all need to be present to maintain and build body weight and muscle mass.
If you are a “grazer”, you would be better off saving up your food/meals to a 4 hour timing interval. Small frequent meals, rev the body and metabolism and often burn more calories. You should be having well balanced meals about every 4 hours, but not nibbling in between times. Drink calorie containing beverages such as 100% fruit juice, smoothies and milk as opposed to water all the time. Include protein and fat at each of your meals. Often people trying to gain muscle mass are fearful of including healthy sources of fat in their diet in an attempt to avoid fat mass gain. You require 30% of your calories from fat, so go ahead and re-introduce healthy fats such as nuts and seeds, avocado, olive oil and fish back into your daily routines.
A good training program and adequate rest and recovery are also needed. Your exercise pattern and routines will likely impact your metabolic rate much more than diet alone. Work with a trainer to develop a program that combines both weights and cardio, but won’t contribute to weight loss.