10/11/2023
👀
Spoiler alert: Research shows fasting might not be the answer for athletes - especially female athletes - looking to maintain good metabolic and cardiovascular health.
We see across the board that females have a more difficult time losing body fat than males, especially when it comes to exercise. One method for stimulating fat loss is the theory of training fasted, but we see if females exercise fasted, they are more likely to alter energy-regulating hormones and appetite. In response to exercise without fueling (before and delaying fueling post-exercise), females have a higher concentration of acylated ghrelin and lower concentrations of insulin; both which stimulate energy intake (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3693612/). Exercise-induced energy deficits sufficient to cause weight loss also increases ghrelin concentrations in women, but not in men (https://pubmed.ncbi.nlm.nih.gov/15181038/). The basic premise is that in females, exercise alters energy-regulating hormones in a direction expected to stimulate energy intake; but with males, this does not hold true; infact males have an appetite suppressant response.
We know that exercise is a very strong stressor shown to improved autophagy, modulate gut microbiota, brain health, and increase stress resilience. Research indicates the most effective strategy for increasing autophagy in skeletal muscle is to alter exercise intensities, rather than diet (https://faseb.onlinelibrary.wiley.com/doi/epdf/10.1096/fj.14-267187).For individuals wanting to garner benefits of calorie restriction, time-restricted eating (TRE) may be an option. TRE is about working with chronobiology, to reset circadian rhythms which can improve metabolic health and longevity outcomes ( https://www.mdpi.com/2218-273X/11/4/516 https://www.mdpi.com/2072-6643/13/5/1405).
Many women will contend that fasting works well for them. And it might actually work to some degree for the first three months, because nearly any diet will yield some effects in the short term. The long-term effects for female athletes, however, is endocrine dysfunction, increases in abdominal fat, more depression, and a backlash of subsequent fat gain (https://onlinelibrary.wiley.com/doi/pdf/10.1038/oby.2007.542). The bottom line is that female athletes should focus on fueling themselves adequately so that they are able to cover all metabolic processes and also the energy expended during exercise. To improve training adaptations and performance, fueling before exercise and recovering from exercise are equally critical (https://doi.org/10.1016/j.jsams.2010.03.002.
Learn more >>>
https://www.nature.com/articles/s41574-020-0318-z
https://www.embopress.org/doi/full/10.15252/emmm.202114418
https://journals.physiology.org/doi/full/10.1152/japplphysiol.00550.2015
https://journals.physiology.org/doi/full/10.1152/japplphysiol.01146.2017
