I am 20 years old and 5″4 weighing 121 pounds. I am a distance runner and want to lose 10 pounds to run lighter and get my PR. If my BMR is 1,908 calories, and I am cutting my calories to 1,200 a day to lose weight, but also going on distance runs, will this slow my metabolism? I need to lose the 10 pounds by the end of the summer, but I want to do it safely and the healthy way. Do I have to “eat back” the calories that I burn during my runs?
Based on what you have outlined in your question, I don’t think it is necessary to specifically “eat back” the calories that you have utilized. However you should take steps to ensure you optimise your recovery and protect your muscle reserves. Combining intense exercise and a low calorie diet can result in eventual stagnation of fat loss. I would recommend that you include one possibly two cheat days per week, where you allow yourself an excess of calories from whatever foods you want. When following an intense program such as yours, adding a cheat day is a good way to “reset” your body into thinking that food is in plentiful supply, so that it doesn’t go into starvation mode. You should also make sure that following your long distance runs, you have a meal rich in protein and carbohydrates and a small amount of good fats. Providing adequate protein to preserve your muscle mass is important, as its easy for distance runners to become catabolic and burn their muscle mass which in turn can lower metabolism and reduce the rate of fat loss. Consuming oily fish is particularly useful so as to get some anti-inflammatory Omega-3 fatty acids which can also help your joints following long distance runs.