Let’s Talk About Intermittent Fasting and Menopause

Intermittent fasting has attracted interest on social media and among researchers as a simple option for weight loss and improving health and longevity. In the menopause space, intermittent fasting has been popularized as an “innovative way to say goodbye to midlife body composition changes” and uniquely addresses challenges in midlife.

The pursuit of weight loss and the pressure to prevent weight gain in midlife and beyond is palpable for many women. In addition to body dissatisfaction, women over age 45 say that improving their health is the main reason for wanting to lose weight.¹ For example, weight loss is often recommended as a way to prevent diabetes which was addressed in part 1 of this series about health and weight.

We live in a competitive diet marketplace, where each diet and its followers are fighting for our attention, trying to convince us that their diet is the definitive solution for achieving the results we want. With the popularity of menopause in the media, midlife women are increasingly targeted by these competing diet trends, all claiming to be backed by science.

What does the science say about intermittent fasting?

The interest in Intermittent fasting (IF) as a form of dietary restriction is fundamentally a timing strategy manipulating when a person eats rather than what they eat. Numerous IF protocols have been studied, which fall into two main categories including fasting on certain days of the week or limiting eating times to a prescriptive number of hours within each day (ranging from a 4- to 10-h window). Some diet promoters combine IF with food restrictions, such as low-carb, but the premise of IF research is based on the simplicity of following a diet that doesn’t have food limitations.

Does it work?

According to multiple studies, meta-analyses, and systematic reviews, IF diets are no more effective than calorie restriction in achieving weight loss. ^2-5 Furthermore, there are no long-term, randomized, controlled trials that show intermittent fasting produces additional health benefits when compared to healthy and regular eating patterns.

What about the benefits of IF for aging and longevity?

Advocates argue that animal studies show caloric restriction extends lifespan. These folks contend that considering our ancestors’ sporadic food availability, IF may theoretically offer health benefits beyond weight loss – if we just eat less.⁶ Other proponents claim that although time-restricted eating (TRE) yields mild weight loss, health benefits may be possible if we simply finish eating before 5 pm and only within a 4 to 6-hour window each day.⁷ Although it’s recognized by these researchers that longer-term trials are required to confirm these effects, real-world practicality and sustainability are uncertain.

Long-term studies investigating whether IF is an effective strategy for addressing weight concerns and improving health in older women are scarce. Many of these studies are less than 12 weeks in duration and include a handful of participants. This is problematic since arguing that short term dietary restriction results in optimized health is a stretch and not reliable evidence for managing menopause, the challenges of midlife, or long-term weight loss. We will come back to that.

First, let’s unpack a few of the long-term studies investigating intermittent fasting.  

One example is a 2023 randomized, control trial with a 6-month intervention and 12-month follow-up.⁸ In this 18-month trial with 209 participants (average age 58 and 57% female), the researchers compared the effect of alternate-day fasting plus early time-restricted eating to calorie restriction (CR) and standard care (provided a weight-loss booklet). The fasting and CR groups lost an average of 7% from baseline weight at month 6, however, less than half of the fasting participants (compared to 97% of CR participants) said they would continue the weight loss plan. Consequently, by month 18 both the fasting and CR participants had regained weight, and the health benefits observed early in the trial were lost by 18 months.

A 24-month prospective analysis in patients with type 2 diabetes showed that IF and CR resulted in similar weight loss at 12 and 24 months. However, by the end of the second year, participants regained over one-third of the weight that was lost by month 12, and a measure of blood glucose levels (Hemoglobin A1c) increased above baseline in both groups. The authors said this was likely due to the participant’s unwillingness to sustain either diet for the full length of the study.⁹

Similarly, in another randomized, controlled trial with a 12-month follow-up of subjects following modified alternate-day fasting, the drop-out rate was higher in the IF group and there were no differences in weight and fasting glucose at 6 or 12 months.¹⁰

Some proponents argue that modern society’s 3 meals-a-day is the problem that contributes to excessive weight gain and thus meal-skipping is a meaningful solution.⁶ However, a 12-week trial challenged this theory with participants randomized to a 16:8 TRE protocol (skipping breakfast and eating only between 12 and 8 pm) and another group instructed to eat 3 meals per day (meal #1 in the morning; meal #2 a few hours later; and meal #3 sometime between 4 and 10 pm).¹¹ There was no greater weight loss in the TRE group, but the researchers were concerned when they found that approximately 65% of the weight lost in the TRE group was muscle. The authors concluded that skipping breakfast does not have a beneficial effect on weight or health.

The problem with fasting diets

One of the problems is the lack of sustainability. This is a common issue in weight loss interventions. While weight loss is achieved in the short term, maintenance is challenging. Results from a systematic review of high-quality weight-loss studies, requiring at least 3 years of follow-up, more than 5% weight loss, and less than 30% dropout further underscore the issue that in the 8 studies that qualified for the analysis, most individuals regain weight once treatment concludes.¹² Shocking, right??

Although weight loss and regain may seem harmless, it’s not. In addition to the psychological toll (frustration, distress, shame, and guilt), there is a physiological impact on bone, muscle, cardiovascular health, and cancer risk with weight cycling (repetitively losing and gaining weight).¹³

Numerous factors hinder long-term weight loss and lead to weight regain in midlife, including sleep disturbances, menopausal symptoms, and environmental stressors. But, fasting may aggravate these symptoms.

Participants in the 18-month trial described previously said that side effects, such as fatigue, constipation, and headaches were challenges for continuing the IF diet. ⁸ A reduction in activity was observed among postmenopausal women who were limited to a 4 to 6-hour eating window. ⁷ And, when subjects were provided with an Oura ring for data collection in another study, a significant reduction in daily movement was observed in the fasting group. ¹¹

As noted previously, fasting comes with a risk of excessive loss of lean mass or muscle. Restricted eating windows may also lead to inadequate protein intake, potentially worsening muscle loss. In a 12-month trial by Liu et al, participants were randomly assigned to either daily calorie restriction alone or a calorie-restricted diet and eating between 8 am and 4 pm (thus fasting from 4 pm to 8 am). ² Both diets provided 15 to 20% of the calories from protein. Based on the average weight of the participants, I estimated that the women’s protein intake in this study was between 0.5 to 0.6 grams per kilogram per day which is less than half of the daily recommendation for aging women.

Someone might argue to simply eat more protein within the 8-hour eating window. Not a bad idea. However, increasing protein intake on a calorie-restricted diet would be at the expense of other nutrients which is another problem that I will cover in part 3 of this series about the Keto Diet. The issue here is the low calorie intake which contributes to not only a low protein intake – but long term would constitute a low intake of vital nutrients for healthy aging.

Not eating enough calories and protein, along with the body’s reduced ability to build muscle as we age (referred to as anabolic resistance) is a recipe for exacerbating muscle loss and contributing to weight/fat regain.¹⁴ Moreover, older women are at risk for osteoporosis and sarcopenia, conditions linked to insulin resistance, diabetes, increased falls, fracture risk, and compromised mobility, underscoring the possible negative effect on musculoskeletal health when considering IF.

Calorie restriction has a downside 

People will believe what they want to believe. However, numerous long-term, rigorous studies do not support IF for sustainable weight loss or improving health outcomes. On the other hand, several studies link dieting and delayed eating to a higher risk of overeating, binge eating, and other eating disorders.^15-16 Furthermore, the menopause transition is recognized as a period of increased vulnerability to the development of eating disorders.¹⁷ Often underdiagnosed, the prevalence rate of eating disorders is over 7% of older women while only one-fourth receive help or seek treatment.^18,19

Although its hotly debated whether calorie restriction and dietary restraint has a positive or negative impact on health, aging, and disease,^6,20 it’s really hard be a clinician with nearly two decades of clinical nutrition experience to look past the hundreds of people of all ages whose eating disorder started with a well-intentioned calorie deficit.

Eating disorders are a complex bio-psycho-social illness, but the premise of activating a “magical” metabolic switch with chronic energy deficiency which will melt fat away, increase lifespan, and manage menopausal symptoms, decrease anxiety, and improve sleep ignores this body of literature. Given that weight loss is praised vs questioned and screening for all types of eating disorders in midlife health is not common practice, it seems a bit risky to me when clinicians who specialize in midlife health prescribe dieting and calorie restriction.

Will IF help you feel better?

For women who are concerned about their health and distressed about their body dissatisfaction, I completely understand the discomfort and the sense of urgency to find a solution to help you feel better. I get that eating healthfully and trying to find the energy to work out in midlife is not always easy. And, for many women, dieting and weight loss has usually been a way to solve the discontent about one’s weight and body image.

However, let’s start with the fact there is not a one-size-fits-all approach to the timing of meals and snacks. Some people enjoy 3 meals a day, while others enjoy 3 meals and snacks – at different times based on their lifestyle and hunger patterns – and their weight and health is fine. The idea that a person can meet their nutrition needs within a limited period or based on some external definition of the “perfect” time to eat is not practical.

• Is it realistic to think that you are never going to eat dinner with your family or join friends for an evening meal at a restaurant (if you’re supposed to fast after 5 pm)?
• Are you simply going to avoid invitations to eat a meal or brunch before 12 pm (if you’re skipping breakfast)?
• What about when you travel for work or leisure and need to be flexible with eating schedules?
• In the case of alternate day fasting, how will that work if the “fasting day” is the day of your son or daughter’s wedding?

Will this make you feel better? It may provide a sense of structure and control at first, but in the long run, IF is no different than any other form of calorie restriction that comes with more food rules and will likely be a source of disruption (and possibly harm) to enjoying this stage of your life.

Undieting

It may be time to recognize diets, and the diet cults, for what they are. If you find a pattern of food and eating that works for you – and you can sustain it forever and ever (while adequately nourishing your body without relying on a pillbox of supplements), then that’s great!

But, for most people, its just really hard to maintain these fad diets, restrictive eating plans, and weight loss – and thus we exist in a multi-billion dollar competitive diet marketplace.

Undieting means reclaiming regular meals and foods you enjoy! It does not mean that you should simply throw up your hands and ignore mindfully eating a variety of nourishing foods.

However, whether it’s through learning about the principles of intuitive eating, receiving help with a balanced, inclusive approach to food and eating, or getting support for managing body dissatisfaction, the long-term health benefits of these approaches are evidence-based and compatible with empowering women to live their best life in midlife and beyond.

Coming up in part 3, I will unpack the Keto diet for midlife health!

References:

1. https://www.comparethemarket.com.au/health-insurance/features/what-motivates-us-to-lose-weight/
2. Liu D, Huang Y, Huang C, et al. Calorie Restriction with or without Time-Restricted Eating in Weight Loss. N Engl J Med. 2022;386(16):1495-1504. doi:10.1056/NEJMoa2114833
3. Sharma SK, Mudgal SK, Kalra S, et al. Effect of Intermittent Fasting on Glycaemic Control in Patients With Type 2 Diabetes Mellitus: A Systematic Review and Meta-analysis of Randomized Controlled Trials. touchREV Endocrinol. 2023;19(1):25-32. doi:10.17925/EE.2023.19.1.25
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5. Cioffi I, Evangelista A, Ponzo V, et al. Intermittent versus continuous energy restriction on weight loss and cardiometabolic outcomes: a systematic review and meta-analysis of randomized controlled trials. J Transl Med. 2018;16(1):371. Published 2018 Dec 24. doi:10.1186/s12967-018-1748-4
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8. Teong XT, Liu K, Vincent AD, et al. Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial. Nat Med. 2023;29(4):963-972. doi:10.1038/s41591-023-02287-
9. Carter S, Clifton PM, Keogh JB. The effect of intermittent compared with continuous energy restriction on glycaemic control in patients with type 2 diabetes: 24-month follow-up of a randomised noninferiority trial. Diabetes Res Clin Pract. 2019;151:11-19. doi:10.1016/j.diabres.2019.03.022
10. Trepanowski JF, Kroeger CM, Barnosky A, et al. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Intern Med. 2017;177(7):930-938. doi:10.1001/jamainternmed.2017.0936
11. Lowe DA, Wu N, Rohdin-Bibby L, et al. Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity: The TREAT Randomized Clinical Trial JAMA Intern Med. 2020;180(11):1491-1499. doi:10.1001/jamainternmed.2020.4153
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13. O’Hara, L., & Taylor, J. (2018). What’s Wrong With the ‘War on Obesity?’ A Narrative Review of the Weight-Centered Health Paradigm and Development of the 3C Framework to Build Critical Competency for a Paradigm Shift. Sage Open, 8(2). doi.org/10.1177/2158244018772888
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15. Levinson, C. A., Fitterman-Harris, H. F., Patterson, S., Harrop, E., Turner, C., May, M., Steinberg, D., Muhlheim, L., Millner, R., Trujillo-ChiVacuan, E., Averyt, J., Peebles, R., Rosenbluth, S., & Becker, C. B. (2023). The unintentional harms of weight management treatment: Time for a change. the Behavior Therapist, 46(7), 271–282.
16. Montani JP, et al. Dieting and weight cycling as risk factors for cardiometabolic diseases: who is really at risk? Obes Rev. 2015 Feb;16 Suppl 1:7-18
17. Mangweth-Matzek B, Hoek HW, Rupp CI, Kemmler G, Pope HG Jr, Kinzl J. The menopausal transition–a possible window of vulnerability for eating pathology. Int J Eat Disord. 2013;46(6):609-616. doi:10.1002/eat.22157
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