Reducing excess body fat is a common goal with exercisers.
It turns out that down-regulation of stress hormones is the highest priority when looking to reduce excess body fat, in particular when it is around the belly.
Cortisol is a stress hormone, that, when chronically elevated contributes to the storage of body fat (in particular, belly fat). This has been shown by several studies, including by Moyer et al in 1994, which showed that a higher waist to hip ratio (WHR) in overweight women was associated with higher serum cortisol levels after being exposed to stressful situations.
Fasting, a popular current dietary trend – such as the 5/2 diet, or 16-8 diet, which involves either a daily or weekly “feeding” window alongside a “fast” window, has been shown to significantly elevate serum cortisol levels. (interestingly, caloric restriction has also showed this trend in some studies)
This has been shown in a systematic review of over 13 seperate studies by Kakamura, Walker and Ikuta.*
Fasting may be a popular “hack,” but perhaps it is the single fastest way for us to signal to the nervous system that we are in a state of scarcity? That we need to activate our stress response (cortisol and/or adrenaline) to mobilise the system to find food.
Over time, this will lead to a chronically stressed state, with potential muscle loss (catabolic) and fat gain. Other signs that the stress hormones are overly active may include poor sleep (getting to sleep, or staying asleep), anxiety and more.
(Note, also a “lack” of abdominal adiposity does not mean that stress or cortisol is low)
So, if we don’t cut calories and don’t fast to lose weight, how do we lose fat?
Restore metabolism (food choices, food frequency and breath work), increase muscle mass (lean muscle mass is metabolic), down regulate lifestyle stressors.
