Is Intermittent Fasting Beneficial for Women?
Intermittent fasting has gained a lot of attention and momentum over the last few years and given the reported related health benefits, it’s a topic I’m often asked about in my clinical practice. As a naturopath and nutritionist who has seen a surge in popularity of diets that involve intermittent fasting, the most important thing to do when considering a new diet is to ask yourself, is this diet right for you as an individual – particularly as a woman.
What is Intermittent Fasting? Intermittent fasting is an eating pattern that cycles between periods of eating and fasting on alternate days or set hours in the day. It doesn’t specify which foods you should eat but rather when you should eat them. So, it’s not a diet in a conventional sense, but more of an eating pattern. There are different types, such as the popular 5:2 method, which involves eating normally 5 days of the week, while restricting calories to 500-600 on two non-consecutive days of the week. A popular alternative is the 16:8, which involves daily time restricted eating, reducing your “eating window” to 8-10 hours, for example eating between the hours of 12pm – 8pm.
What are the proposed benefits? There are many published articles, from personal blogs to academic journal articles, that document the health benefits associated with intermittent fasting. These include, but are not limited to:
Weight loss and weight management
Improved cardiovascular health
Lower risk of diabetes via reducing insulin resistance
Improved brain health
Reduced inflammation and oxidative stress
May prevent cancer
May increase lifespan
Should women fast? While the research largely shows many positive benefits, the sample sizes tend to be mostly limited to men – both male rodents and male humans. Human studies have mainly been limited to observational studies of religious fasting (such as during Ramadan) with modest sample sizes that lack in reporting other contributing factors, such as physical activity. The results that have been found through male samples cannot be simply extrapolated for women, as hormonally we are very different.
For example, a small study in 2013 of 15 adult overweight or obese women detailed alternate day fasting for 8 weeks and resulted in weight loss and a decrease in coronary artery disease risk factors.
However in a larger study piloted in 2011 of 107 overweight or obese young women, results demonstrated that intermittent fasting for 6 months was just as effective as continuous energy restriction for weight loss alongside improvements in a number of risk markers for cancer, diabetes and cardiovascular disease.
A 2012 study involving 29 healthy women showed that fasting resulted in a reduction of white blood cells (leukocytes) and pro-inflammatory cytokines following intermittent fasting for Ramadan, reducing overall inflammation in the body.
Conversely, a 2017 systematic review found a small study of 9 healthy weight women, who reported increased feelings of hunger, worse mood, heightened irritability, difficulties concentrating, increased fatigue, eating-related thoughts, fear of loss of control and overeating on non-restricted days, following four weeks of intermittent fasting. This study, although small, highlights the potential disadvantages of intermittent fasting for women who are already a healthy weight.
A 2018 study performed at the Lithuanian Sports University observed eleven overweight women undergoing a two-day fast. Compared to their regular state (eating a regular diet), the women who fasted experienced an increase in sympathetic nervous activity. This increase is yet to be seen in men under similar conditions. This suggests that fasting could trigger a bigger stress response in women, compared to men.
When should intermittent fasting be avoided?
If you are a diabetic or have dysregulated blood glucose levels – Going long periods of time without food causes a drop in blood glucose levels that can lead to a potentially life-threatening hypoglycaemic state for diabetics.
If you are trying to conceive or have a history of amenorrhea – Adequate micro and macro nutrients are required for the endocrine system to function efficiently, restrictive eating can lead to hormonal imbalances and irregular menstruation.
If you have a history of an eating disorder – Most diets are about control and restriction, which over time can result in an unhealthy relationship with food.
If you have an issue with your thyroid – Your body requires a certain amount of carbohydrates every day to convert T4, the storage form of thyroid hormone, into the active T3 form. Fasting and reducing the quantity of carbohydrates in your diet can interfere with this conversion, ultimately slowing your metabolism and making weight loss more difficult.
If you are chronically stressed or don’t sleep well – Prolonged release of the stress hormone cortisol interferes with our ability to maintain a healthy weight and has been shown to increase the deposition of fat around our middle. Sleep deprivation is a stressor to the body and thus stimulates cortisol. Both leptin and ghrelin, key hormones in the control of body fat and appetite, are disrupted by sleep disturbance.
If you are a still growing – During periods of intense growth, such as childhood and adolescence, fasting isn’t recommended. Your teens can be a time of intense self-scrutiny and comparison and is often when many young women begin dieting. It’s a sensitive time to change food habits, even when it’s appropriate.
If you are pregnant or breastfeeding – Like childhood, pregnancy is a period of intense growth. Even though weight gain during this time is wanted, many women feel uneasy about gaining weight. Women who are especially body conscious or who were wanting to lose weight before pregnancy may still think about weight loss during this time. Even if weight management is recommended by your medical professional, fasting is not appropriate during this time. This is a time in a woman’s life where she requires more nutrients to help grow and feed her baby, fasting can limit her ability to reach these daily requirements.
Current research shows potential advantages of intermittent fasting for obese and overweight women, however more research is needed to understand the benefits for other groups of women. Given our body is actually already well equipped for intermittent fasting – as it benefits from fasting naturally while we sleep each night – does this mean we need to extend these hours to increase the advantages?
If you still want to try intermittent fasting, there are ways to dip your toe in. You might start by keeping a food journal for a few days. Get a sense of what you’re eating, how much, and how often. Are you eating late at night and snacking throughout the day? Do your portions tend to be big and fill you up, or do you prefer lighter meals? Are you getting protein at every meal? Veggies? Once you have some more awareness of your baseline, you can experiment with intermittent fasting.
Here are a couple of ways to do that.
Begin by stretching the time between eating. If you normally snack between meals, what happens when you stop? Do you feel ravenous, dizzy, and angry? Does the hunger ebb and flow? Do you feel totally fine?
Try lengthening the time between your last meal in the evening and your first meal the next morning. For example, if you usually eat your last meal at 8 pm, and then eat breakfast at 7am (fasting 11 hours), try eating your last meal at 6pm, and eating breakfast a little later, at 8 or 10am (fasting 14-16 hours).
Monitor yourself with curiosity, kindness, and honesty. If you’re feeling energetic, mentally sharp, and all systems are regular, continue with a gentle intermittent fasting approach, or try stretching the fasting window a little more.
Stop intermittent fasting if:
If you’re feeling obsessive, unhinged, or consistently lethargic, ease off.
Your menstrual cycle stops or becomes irregular
You have problems falling asleep or staying asleep
Your hair starts falling out more than usual
You start to develop dry skin or acne
You’re noticing you don’t recover from workouts as easily
Your injuries are slow to heal, or you get every bug going around
Your tolerance to stress decreases
Your moods start swinging
Your heart starts going pitter-patter in a weird way
Your digestion slows down noticeably
You always seem to feel cold
Don’t get caught up in “doing it right.” As I’ve seen from guiding hundreds of people to their weight loss goals, there are many ways to transform bodies, and none of those methods require you to be perfect.
What to do if fasting isn’t for you? How can you get in shape and lose weight if you find intermittent fasting isn’t a good fit? Learn the essentials of good nutrition. Fasting or not, you can’t go wrong focusing on meal quality. Prioritise lean proteins, colourful veggies and fruits, healthy fats and complex carbohydrates. Crowd out treats, sugary beverages, and processed foods. Cook and eat whole foods. Move your body regularly. Stay consistent. (And if you’d like some help to do all of that, make an appointment.)
Sure, intermittent fasting may be popular. And maybe your brother or your boyfriend or your husband or even your dad has found it works really well for them. But women are different than men, and our bodies have different needs. Listen to your body. And do what works best for you.
In my practice, I encourage people to tune in with their body and take note of how a particular way of eating makes them feel and function, as we are each have unique needs and one diet will never be healthy for everyone. If you’re feeling unsure if it is the right option for you, reach out to your local qualified health professional or nutritionist to discuss your individualised needs.