From weight loss to gut health, anti-aging and longevity, intermittent fasting shows many benefits for our health and wellness. However, many of these benefits can be reaped from less extreme variations of fasting, such as calorie restriction, macronutrient timing and time restricted eating. Intermittent fasting is one of the topics I get asked about most by my clients, and that I am asked to give my expert opinion time and again for the publications I write for (check out my piece on intermittent fasting and anti-aging for AEDIT here, or my piece for New Beauty magazine on intermittent fasting and weight loss here), but is it healthy, or even safe for women?
Here is what the research says, and what works and doesn’t work from my experience using intermittent fasting in my clinical practice.
When considering diet and nutrition interventions biological gender matters, as men and women have such different endocrine systems and biological cycles and therefore their energy and nutrient needs differ. Whilst clinical studies often show positive outcomes on many health markers after periods of intermittent fasting it is rare that these studies are actually performed on women (due in part to women between the ages of 18-30 being of childbearing age), so there is little clinical data available for intermittent fasting and its effects on women’s health.
Additionally, we can look to evolutionary biology for clues as to why men may be better adapted to longer periods without food. In Paleolithic times it was typically the males who would hunter/gather for food, meaning longer stretches of time away from the home and without eating. The females would stay behind to look after the children, and have access to food on a more regular basis.
As mentioned above, women’s nutritional needs differ from men’s due to their biological differences, mostly in regards to their endocrine systems and related biological cycles. A women’s endocrine system and biological cycles are far more complex than that of a male’s and therefore different diet interventions may have different effects.
As thyroid and adrenal health is synergistic to endocrine function, it is important to consider this in regards to the stress that intermittent fasting can put on the body. If your brain senses you are in starvation mode this can release a cascade of stress hormones such as cortisol and adrenaline that can put strain on your adrenal glands and thyroid function.
If you are insulin resistant, suffer from chronic inflammation, or both (they often go hand in hand in metabolic disease) then you may not be able to use your stored body fat for fuel, or be able to shuttle the energy from food into your body’s cells. This can actually cause your body to go into starvation mode and its trigger stress related effects, even if you are eating regularly.
Intermittent fasting can exacerbate this problem, negatively affecting thyroid health. A healthy, well-functioning thyroid is one of the keys to a healthy metabolism and being able to lose body fat, so in this case intermittent fasting may actually work against healthy, sustainable weight loss.
As part of my 8 Week Lean and Clean Program and my Private Coaching Programs I have tools that help my clients reap the benefits of intermittent fasting without any negative effects on their thyroid or adrenal health, and that actually boosts their metabolic rate rather than slowing it down.
I use a ‘stair-step’ process to get them safely to an 18 hour fast, and each step should feel easy and comfortable before moving on to the next:
In my professional opinion 18 hour fasts should only be undertaken by those in optimum health, and definitely not by those who are pregnant, breastfeeding, ill, underweight, suffering from adrenal or thyroid dysfunction, or those under extreme stress. Personally a 16 hour fast is the longest I feel comfortable with, and I only do this after a large holiday or celebratory meal. I typically fast 12-14 hours overnight almost every day, and find that this helps keep my body fat in check without losing any lean muscle mass (essential for a healthy metabolism).
Are you looking for a science based, experience proven weight loss program that actually works? Check out my 8 Week Lean and Clean Program – its not a quick fix, but it gets quick results! Sign up before 12/31 to get access to a VIP coaching call on 1/1/21!