Why it’s possible to gain weight when training for a marathon.
As springtime rolls around, many people will be starting a training program for marathons, half marathons, 5ks, etc. Some will be using this as a way to lose weight and get in better shape. While it is true that running can improve your overall well being and fitness level, it does not mean that you are exempt from a “proper diet”. I have heard stories of marathon runners eating whatever they want because they “ran”. The problem with this is, your body still has to process and store the unhealthy food you are eating regardless of how far you ran or how many calories you burned.
On average, an individual who does an 18 mile training will burn roughly 2,000 calories. The total amount will vary according to many factors but that is not the focus if this post. (Pace can be a big determinant of calories burned and isn’t always more the faster/harder one runs. At an aerobic pace our bodies will burn more fat then if we run harder and force the body to utilize the small supply of glucose.) To maintain a healthy body weight, the National Heart Lung and Blood Institute recommends moderately active females consume between 1,800 and 2,200 per day while moderately active adult men require between 2,200 and 2,800 calories each day. Consider that if the average person consumes roughly 2,000 calories a day and then burns 2,000 calories on a long training run, they will have to consume twice the amount of what they typically eat that day just to maintain their weight. This person probably will be hungry all day and most likely snack more and have the mentality they can “eat whatever”. The problem with this is if the person snacks and eats readily available junk food, they will not satisfy their hunger and most likely consume far more then the extra 2,000 calories they burned.
This pattern can continue at a smaller degree during the moderate length runs during the week eventually adding up over time. Weight gain occurs when an individual consumes an excess of daily calories over a period of time. Consuming an extra 3,500 calories a week typically results in about 1 lb. per week weight gain.
Nutrition is very important when training for marathons and half marathons so focus on trying to replace the calories lost with an equal amount of healthy calories from whole foods.