Intermittent Fasting: Follow Up

Apr 30
3 min read

After sharing my thoughts on intermittent fasting in the previous post, several of you asked for more detail on the potential downsides and how the science applies differently to women. Because as some of you already know, I don't (generally) recommend intermittent fasting to my female clients 😲. Yes I said it. Imagine saying that on Instagram 🫣

That might sound a bit off but give me a minute or two and I will explain why. Before I start, this is not medical advice. I'm simply sharing my current scientific understanding so you can make more informed decisions.

Before we get to the more sciencey part, in my anecdotal experience, the women who want to see me for personal training wish to get stronger (for a number of reasons, to improve at their sport for example, or after injury). These women generally have lower muscle mass than what is optimal. So our job is to first build up to a baseline and then work on from that. The strategy requires a higher protein diet 🍗 (protein repairs and builds muscle, simplistically) and getting better and stronger at some very basic lifts (or long-hold standing yoga poses). If that client of mine is intermittent fasting (because they already have low lean muscle mass) they are likely to accelerate muscle loss rather than build more muscle. Read that again. If a woman with already low muscle mass lifts weights but intermittently fasts and doesn't get adequate protein, they can accelerate muscle loss.

This is based on the following 👉🏽 declining estrogen levels already accelerate the natural loss of muscle mass (sarcopenia) and bone density. Some studies suggest that intermittent fasting can speed up this process by elevating cortisol (which promotes muscle breakdown), reducing available amino acids for repair, and potentially affecting hormones such as DHEA 🤔

While intermittent fasting can be effective for some people (it clearly works well for me), the science shows important nuances, particularly around muscle mass 💪🏽, hormonal health, and age-related changes.

If you already have relatively low muscle mass, the drawbacks can outweigh the benefits. Maintaining muscle is one of the most important factors for long-term health, bone strength, and independence as we age. Overly restrictive eating windows can make this more challenging.

In short, although I personally practise "time-restricted eating" and benefit from it, I do not recommend intermittent fasting for most women whose primary goal should be the maintenance of muscle mass, especially those in perimenopause, menopause, or post-menopause. For many women in these stages, a more moderate approach that includes consistent protein distribution across the day and avoiding extended fasts often supports better outcomes for optimal long-term health.

I say this clearly because in 25 years as a personal trainer, I have seen far too many women pushing restrictive protocols that may be working against their long-term health goals. What works metabolically for a younger man or a highly muscular individual does not always translate well for women navigating hormonal shifts.

And remember, all these studies on intermittent fasting that everyone loves to boast about on podcasts, have the studies been done on women over a certain age? Or are most of them done on young, athletic men? Food for thought 🤔

The goal is never to follow a trend. The goal is to support your body intelligently so you can sustain your body and yoga practice for decades to come.

If you have specific questions about this, feel free to reply to this email or speak with me at the studio. Everyone's physiology is different, and what serves one person beautifully may not serve another.