To my dismay, I gained 12 pounds over the 3 months I trained for my first marathon. I tried to console myself with the belief that it was new muscle mass. But it's impossible to gain that much muscle on a 100-pound female frame in that short a time period - without the use of steroids. The 12% increase in body mass was quite obvious on my 4'10" frame, and I could feel it through my tighter clothes. But most alarming, my sluggish run pace!
The culprit... thinking I could eat anything I want since I was training for a marathon. Though nutrition is very important in training for any endurance event, huge portions of pasta and dessert after every dinner (and many lunches) contributed to my diet disaster. I was undermining my training by over-feeding myself.
So, if your goal is to maintain or lose weight as you train for an endurance event, remember: calories in should be equal to or slightly less than calories out. Calories in might increase while training, but there is an upper limit. Anything above it still gets stored as fat - regardless of the amount of exercise.
Of course, weight gain is good if it's muscle mass. To determine if you've gained fat or muscle, monitor your body composition (with metrics such as % fat, fat mass, lean body mass). Many health clubs and gyms offer this service. Just like weight, body composition shouldn't be the only metric you pay attention to, but it can be another data point to measure your progress.
Hi Geri C, I too have been running over 100km per week now for 7 months. I find that after my longer 3 hr runs I do not get hungry for hours after, but my shorter faster runs of 1 hour I come back really hungry. I have managed to maintain my weight at 53kg and I am onlt 5ft. However I have found that heavy foods such as yogurt and red meat contribute to much slower running times.I also have days where I feel like I am really wobbly usually these are my training days directly after a big/long run. I assume that I am retaining fluid. If I stop training for 3 - 5 days I find that I can lose up to 3 kg. So fluid must be a big part of the weight gain. I also agree with you that there are times when I feel that I owe myself an icecream or a treat for such a great run and indulge without really thinking about the consequences. How many calories are too many, does this differ from person to person? Any suggestions? Marree Manchester - NZ