On paper, this doesn’t sound a problem, but in reality, it is. Now, I’m not talking about your 45 minute gym session, I’m talking about hard, intensive training camps or prolonged period of work such as preseason training.
If you combine high energy expenditure with decreased appetite, it could cause large energy deficits as the mismatch between intake and output becomes very high – meaning that many areas of both performance and health can become compromised.
It’s been shown that high volume daily training causes a disturbance in the appetite regulatory system, where functional overreaching can happen in only a few weeks of training.
In true D2EW style, we have a 2017 study by Oshima et al looking at the physiological impact of 9 days, double day training in Japanese American footballers. Despite only 13 athletes participating in this test, the average daily calorie intake at the end of camp dropped from 6175kcal to 4752kcal…a drop of 1,423kcal.
Of which, the performance enhancing nutrient (carbs) dropped from 926g to 747g per day. Now, 747g of carbs is still a lot, but given that they couldn’t maintain this intake for as little as 9 days is somewhat troublesome. I.e. how would this sudden decline look in 3-4 weeks’ time if training volume was maintained (3x higher than normal)?
It’s generally considered that acute stress blunts appetite, where chronic stress typically drives you to want food. Considering that there was a marked elevation in cortisol on day 9 (indicative of stress), there can be an association with physiological stress and appetite suppression.
Despite little changes seen in the hunger hormone ghrelin, it’s evident that there’s some form of connection between hard training, physiological/psychological stress and food intake. For example, levels of tension, depression, fatigue and confusion increased from day 2 to day 9 of camp…does this transient change in mood scores have an impact on appetite?
Either way, the end result is lowered food intake, which is evident in this study and anecdotally from many athletes I’ve work with when their training demand is mega high!
The solution? If you can’t eat your calories, start drinking them…