Clearly in a system as complex as the human body it is a gross oversimplification to assume that all calories are equal. Lifestyle and weight

Stress and overtraining are also essential in the weight loss game with both interplaying with hormones that regulate appetite. Grehlin is known as the hormone that stimulates appetite, while leptin is the “stepaway-from-the-plate” hormone that increases as we start to get full. An increasing number of studies show that sleep deprivation leads to weight gain and loss of lean body mass – both negative outcomes for athletes. Inadequate amounts of sleep (even in the short term) can lower levels of leptin whilst increasing grehlin and cortisol (another hormone that correlates strongly with stress). Higher levels of cortisol are known to increase appetite, but also the drive to consume high impact/energy foods – high sugar, high fat foods. These foods directly act on our brains – lighting up the pleasure centres by releasing the hormone dopamine – and this drive to eat more has nothing to do with calories and everything to do with the hormonal response to our foods. In other words, different foods affect our hormones in different ways, even when calorically identical. High levels of cortisol can also spur on development of insulin resistance and promote inflammation – both factors which can increase the risk of being overweight (or make weight loss efforts very difficult).

Just as the notion of calories in vs. calories out may be outdated, it is also wrong to assume that calories don’t matter at all. They do. But there are other aspects of your diet (and lifestyle) that bear consideration before you start trying to track calories or energy expenditure in an effort to regulate weight. So, while the instinct can be to train more and harder in an effort to get leaner, our hormones may not agree. Instead, looking after your gut, some sleep, relaxation and recovery may be the best workout you can do. Other factors such as getting adequate amounts of sunshine and subsequently Vitamin D can also be important.

Pro triathlete Pip Taylor is a certified sports nutritionist.