Players who understand energy balance, avoid these problems

Calories you burn in training and playing matches need to be in line with the calories you get from the food you intake. Monitoring your eating habits and training intensity (load) can help avoid unwanted weight loss or gain.
NO HIDING: Simple skin-fold tests can give quick feedback during pre-season testing.

At the start of the season players at pro clubs have a 'weigh-in'. If there's a major difference in what they weigh on returning from holiday and their end of season weight, they could be fined!