Q: I would like to gain between 10-15lbs, I have a high metabolism , 40 years old , 5'7, and my weight is 125

A: Short answer: EAT MORE! It's really that simple. No matter how high your metabolism is, you can gain weight by simply eating more. It might need to be a LOT more, but in the end if you eat enough you will gain weight. If you have trouble packing in healthy calories, consider this bulking tool: two slices of whole-wheat bread smothered with natural peanut butter (the ingredients should list only peanuts and salt) and a sliced banana in between. That's about 400-500 pretty healthy calories. Start by adding one of these to your everyday diet and if that doesn't help you start gaining weight, add another one (or two). Just keep eating! Good luck!