Should You be Fasting While Female? Nutritionists Weigh In

Health trends come and go, but the recent buzz around fasting seems here to stay. Why? Because limiting your eating window is a proven way to stay in shape, heal many underlying health issues, kickstart your weight loss and even extend your life. 

Fasting can help almost anyone achieve their health goals...provided it's done safely. With most of the available medical literature focusing on males, however, it's tough for those who are female bodied to figure out exactly how to implement a fasting plan that will deliver the benefits without derailing our health. 

I talked to Functional Medicine Consultant, Dr Shabnam Das Kar, and Nutrition Consultant, Michal Ofer, co-founders of the Metabolic Dietary Solutions (MDS) Program, to discover why and how women should fast—covering the do's, the don'ts and everything in between.

*There are many definitions of fasting. In the discussion below, 'intermittent fasting' or 'time-restricted eating' refers to a fast of less than 24 hours.

*This interview was conducted through interview. The answers are a combined effort between Dr Shabnam and Dr Kar.

What happens to our bodies when we fast?

When we fast, our bodies get into fat-loss mode. Fasting makes our bodies switch fuels from using carbohydrates to using our body’s fat stores.

This leads to a condition called nutritional ketosis (very distinct from the dangerous diabetic ketoacidosis), where our bodies produce ketone bodies. Fasting reduces our insulin levels. Reduced insulin levels lead to fatty acids from our body’s fat stores being converted into ketone bodies. Ketone bodies provide a 'cleaner' body fuel.

Fasting also reduces levels of chronic inflammation. Chronic inflammation is like a smouldering fire that goes on in the body. Higher inflammation levels are related to about 95% of diseases like heart disease, stroke, dementia, mood disorders, and autoimmunity disorders.

Intermittent fasting increases levels of Growth Hormone (GH) in your body. Optimal GH is associated with higher muscle mass, and better bone and brain function.

Our bodies are designed so that we need intervals of eating interspersed with breaks of fasting. Your gut is busy digesting and assimilating food when you are eating. The fasting period provides it with the resting phase. Both are equally important.

Does fasting affect women differently?

Most women [in our program] do not report anything different from men. Our program found some men losing weight faster than women, but our sample size is not significant enough for us to comment on this. A few women reported a change in their menstrual cycles, but this is usually temporary. However, weight loss in women with polycystic ovarian syndrome (PCOS) has helped them in regularizing cycles.

There are so many ways to fast, it can get really confusing. What's your advice to women who aren't sure what routine is right for them?

The most crucial factor is to 'know your why'. What benefits are you looking for? If you have never fasted or tried time-restricted eating before, start with a 12:12. This means you are eating for 12 hours, and you are fasting overnight for 12 hours. In practical terms, how does this look? You finish the last meal of the day before 7pm, and you do not eat until 7am the next day. You can have 'fasting fluids'  like water, herbal tea etc. during your fasting period. Once you are comfortable with 12:12, you can gradually increase your fasting window to 14, 16 or longer hours.

 

What advice do you have for someone who's completely new to fasting—how can they prepare, and what should they be aware of?

First and foremost, plan it properly. You don't want to start an intermittent fasting program or a time restricted eating program when you have a hectic social calendar. Let's say you have the festival season coming up or you have weddings to attend, that is not the time to start fasting.

If you cook for your family, cook ahead of time. You don’t want the smell of cooking food to trigger your brain’s eating centres and disrupt your fast. Stay busy! This is one of the best strategies.

On our program, we also discuss your relationship with food. Are you a stress eater? Do you look at food as a reward for exercising? We strategize to overcome these challenges.

There are a lot of misconceptions around fasting. How do you respond to these?

Some of the most typical questions we get around fasting are, number one, it will cause muscle loss. Now studies have shown that fasting does not cause muscle loss. A low-calorie diet causes a whole lot more muscle loss. Next is about metabolic rate.

In studies where they compared people on a calorie-restricted diet with intermittent fasting, they found that intermittent fasting did not reduce the metabolic rate.

Another big one is not getting adequate nutrition. In our program we recommend nutritionally dense food. However, relying on only food to provide all your nutrients is unrealistic. This is where targeted supplementation comes in.

People are also concerned about hypoglycemia. This is a big one for people with diabetes who are on medications. Most often, people need to stop and or reduce their medications [before fasting]. Therefore they need support from a knowledgeable healthcare provider.

We always have a one-on-one video call before people are on-boarded to our Program. This is a time to bring up their questions.

What are some of the biggest obstacles women face when starting their own fasting routine?

One of the biggest mistakes women make is to do a deep dive into a long fast before building their 'fasting muscles'. Another big mistake is to add prolonged fasting at a stressful time in their lives or when not sleeping well. The mental-emotional side of their lives is vital to their success.

What female-specific conditions or health complaints can fasting help treat?

The biggest one is weight loss. The other big one is PCOS. If you're menopausal, intermittent fasting [or] time-restricted eating will not bring back your depleted levels of estrogen, progesterone, and testosterone to premenopausal levels. However, women tend to gain weight after menopause. The primary factor deciding your weight gain is whether you are insulin resistant. The insulin resistance can be addressed with TRE/IF, but it doesn't restore hormone levels.

Who, in particular, would benefit from fasting, and is there anyone who shouldn't do it?

I would say almost everyone, but it depends on the type of fasting and your goals.

The top benefit for a lot of people is weight loss, but there are benefits beyond the numbers on the scale. These include lower levels of triglycerides, lower blood pressure, lower risk of dementia and diabetes, better mood, improved autoimmunity symptoms, improved brain function, alleviating PCOS, and many more.

Who shouldn’t do it? Pregnant women. They can follow 12:12, but we wouldn't recommend longer fasts. Those with eating disorders, and people who are already too lean are the other major categories. Another conditional category is people who have diabetes and who are on multiple medications. They need support from a knowledgeable healthcare provider who knows how to reduce diabetes medication.

You combine fasting with a low-carb diet at the MDS Program. Why? 

Most of the patients we take care of have insulin resistance. They have a problem where the body’s insulin-carbohydrate system is not working well, which results in excess weight,  PCOS, hypertension, abnormal lipid markers or mood issues. Insulin resistance can show up in many different ways.

For 95% of people dealing with a weight challenge, it is because of insulin resistance. If they are insulin resistant, a low carbohydrate diet works much better than a low-calorie diet. However, 5 to 10% of people are not insulin resistant. For them, probably a low-fat diet may work better. Different things work for different people.

Pre-diabetes is extremely common. One in three Albertans is pre-diabetic, and many don't even know that! For people with insulin resistance, a low(er) carbohydrate diet and intermittent fasting work exceptionally well.

Another primary reason for combining intermittent fasting with low carb is the reduction in hunger. Our program often has people saying that they are surprised at how little they can eat, and this is not through exercising will power and counting calories!

There is no single best diet for everyone. The most important thing is what works best for you. Women find TRE/IF much more comfortable to stick to than a low-calorie diet or eat-less-move-more programs, both of which do not work long-term.

You cannot overcome a bad diet with longer fasts and 'magic' supplements. Food is way more than calories—food sends signals to your gut microbes, and your genes, and your brain. What you eat, when you eat, and in what order you eat are all important. Eating carbohydrates last, versus eating them first during a meal, dramatically changes the metabolic response to your food.

If you want to get started with fasting, or find out more, reach out to Shabnam and Michal today to book a consultation. If you're just looking to switch up your dietary habits, there's a whole network of dietitians and nutritionists available on Which Doctor who can help you develop a customized plan that works for you. 

Catherine Morris

Writer

Catherine Morris is an award-winning journalist with a bad case of wanderlust and a passion for all things health and wellness. Originally from Northern Ireland, she worked as a news and feature writer for media outlets in the UK, South Africa, France and the Caribbean before settling in Canada. Catherine now lives in Alberta with her husband and rescue mutt and spends her time happily exploring the great outdoors with both.