Is Fasting Helping Your Health — or Undermining It?

Fasting is often promoted as a smart strategy for weight loss, metabolic health, and healthy aging. But during perimenopause and menopause, the conversation deserves more nuance.

At this stage of life, the goal is not simply to eat less. The goal is to preserve muscle, protect bone, support metabolic health, and maintain the energy and strength to fully live your life. Research shows that the menopausal transition is associated with declines in muscle mass and strength, along with increases in visceral fat and cardiometabolic risk, making adequate nutrition and consistent strength training even more important (Menzies et al., 2024; Maltais et al., 2009).

For some women, fasting may feel helpful in the short term. But if it leads to under-fueling, missed protein, lower training quality, rebound hunger, or chronically low energy intake, it may quietly work against the very systems we are trying to protect. Low energy availability has been linked to disruptions in metabolic function, hormonal health, bone health, and exercise performance in active women (Slater et al., 2017; Heikura et al., 2021).

Why It Matters More in Perimenopause and Menopause

As estrogen declines, the body becomes less forgiving of inconsistent fueling. The menopausal transition is associated with progressive reductions in skeletal muscle mass and function, which is one reason experts emphasize resistance training and adequate protein intake during and after this phase of life (Menzies et al., 2024; Agostini et al., 2018).

That is why a strategy built around “just eat less” can be misleading. It may reduce calories, but it can also reduce the nutritional support your body needs to maintain lean tissue, recover from exercise, and stay resilient over time (Agostini et al., 2018).

The Real Risk: Under-Fueling

One of the biggest misunderstandings in women’s health is assuming that less food automatically means better health.

In reality, longevity depends on having enough energy and nutrients to maintain muscle, support training adaptation, and protect bone and metabolic function. Low energy availability occurs when the body does not have enough energy left to support normal physiological function after exercise is accounted for (Slater et al., 2017). In active women, this can impair recovery, bone health, metabolism, and overall resilience rather than improve long-term health (Slater et al., 2017; Heikura et al., 2021).

This is where fasting can become problematic. If you skip breakfast, delay protein intake, exercise without enough fuel, eat lightly all day, and then feel tired, flat, or overly hungry later, the issue may not be lack of discipline. It may be a lack of support.

Muscle Is a Longevity Asset

Muscle is not just about appearance. It supports blood sugar regulation, balance, mobility, independence, and resilience as we age. The decline in muscle mass and strength becomes more pronounced across the menopausal transition, making muscle preservation a central priority for healthy aging (Menzies et al., 2024; Maltais et al., 2009).

This is also why fasting deserves a closer look. If fasting causes you to miss opportunities to eat protein across the day, or if it compromises your strength training performance, it may not be a longevity-supportive strategy. Higher protein intake, especially when paired with resistance training, has been shown to support greater gains in skeletal muscle mass and strength in older women (Nabuco et al., 2019).

Bone Health Needs Fuel Too

Bone is living tissue. It responds to mechanical loading, but it also depends on adequate nutritional support. When energy intake is too low, bone health can suffer. Reviews on low energy availability in exercising women have identified impaired skeletal health as a major concern (Slater et al., 2017; Popp et al., 2022).

This matters even more during perimenopause and menopause, when bone loss accelerates. Well-designed resistance training and impact-based exercise programs can improve bone strength and functional performance in postmenopausal women when appropriately supervised (Watson et al., 2018; Kistler-Fischbacher et al., 2021).

You cannot build resilient tissue from a place of chronic depletion.

What About Metabolic Health?

This is where the fasting conversation often gets oversimplified. Some forms of time-restricted eating have shown improvements in insulin sensitivity, blood pressure, and oxidative stress in certain populations (Sutton et al., 2018).

But context matters. One of the most frequently cited studies in this area was conducted in men with prediabetes, not active women in perimenopause or menopause (Sutton et al., 2018). That does not make the findings irrelevant, but it does mean they should not be generalized to women who are also trying to preserve muscle, protect bone, recover from exercise, and maintain stable daily energy.

A strategy can improve one metabolic marker in a controlled setting and still be the wrong fit for a woman whose larger goal is strength, vitality, and long-term function.

A Better Question to Ask

Instead of asking, Should I fast?

Ask, Is the way I am eating helping me build the kind of body that supports longevity?

For most active women in perimenopause and menopause, that means enough total energy to support both exercise and daily life, protein distributed across the day, fueling around training, and resistance training to preserve muscle and bone. The evidence supporting higher protein intake and resistance training in older women is much stronger than the evidence for fasting as a universal longevity strategy in this population (Agostini et al., 2018; Nabuco et al., 2019).

A More Supportive Approach

Rather than asking your body to do more with less, think about giving it what it needs to adapt well.

That might look like eating a protein-rich breakfast instead of delaying food until late morning. It might mean having a small snack before training, especially if you exercise early. It might mean being more intentional about post-workout nutrition so your body has the raw materials to repair and rebuild. Older women who pair adequate protein with resistance training see better outcomes in muscle mass and strength than those with lower protein intake (Nabuco et al., 2019).

This is not about eating perfectly. It is about eating in a way that aligns with your physiology and your goals.

Key Takeaway

Fasting is not automatically harmful, and it is not automatically helpful. But during perimenopause and menopause, it should be approached with far more care than most headlines suggest.

If fasting leads to missed protein, low energy, reduced training quality, poor recovery, or chronic under-fueling, it may quietly undermine muscle, bone, metabolism, and long-term vitality. The research on low energy availability, menopause-related muscle loss, and the benefits of adequate protein plus resistance training points in the same direction: under-fueling is not a smart longevity strategy for active women (Menzies et al., 2024; Nabuco et al., 2019; Slater et al., 2017).

Longevity is not built on deprivation. It is built on strength, nourishment, and the consistent support of the systems that carry you through life.

Performance is the foundation of longevity.

That means eating to support muscle, bone, energy, and recovery — and training in a way that helps you stay capable, confident, and independent for the long run.

That is a far more powerful strategy than simply eating less.

References

Agostini, D., Zeppa Donati, S., Lucertini, F., Annibalini, G., Gervasi, M., Ferri Marini, C., Piccoli, G., Stocchi, V., Barbieri, E., & Sestili, P. (2018). Muscle and bone health in postmenopausal women: Role of protein, vitamin D, and exercise. Nutrients, 10(8), 1103.

Heikura, I. A., Stellingwerff, T., Mero, A. A., Uusitalo, A. L. T., Burke, L. M., & Ruohola, J.-P. (2021). Low energy availability in female athletes: From the lab to the field. European Journal of Sport Science, 21(4), 507–517.

Kistler-Fischbacher, M., Weeks, B. K., & Beck, B. R. (2021). The effect of exercise intensity on bone in postmenopausal women: A systematic review. Bone Reports, 14, 100969.

Maltais, M. L., Desroches, J., & Dionne, I. J. (2009). Changes in muscle mass and strength after menopause. Journal of Musculoskeletal & Neuronal Interactions, 9(4), 186–197.

Menzies, C., Levinger, I., Marino, F., et al. (2024). Menopause, female sex hormones, skeletal muscle mass and function: A narrative review. Sports Medicine.

Nabuco, H. C. G., Tomeleri, C. M., Fernandes, R. R., Sugihara Junior, P., Venturini, D., Barbosa, D. S., Deminice, R., Cunha, P. M., Ribeiro, A. S., Schoenfeld, B. J., & Cyrino, E. S. (2019). Effects of higher habitual protein intake on resistance-training-induced changes in body composition, muscle strength and functional capacity in older women. Nutrients, 11(8), 1724.

Popp, K. L., Hughes, J. M., Smock, A. J., et al. (2022). Impact of low energy availability on skeletal health in exercising women. Current Osteoporosis Reports, 20(1), 1–14.

Slater, J., Brown, R., McLay-Cooke, R., & Black, K. (2017). Low energy availability in exercising women: Historical perspectives and future directions. Sports Medicine, 47(2), 207–220.

Sutton, E. F., Beyl, R., Early, K. S., Cefalu, W. T., Ravussin, E., & Peterson, C. M. (2018). Early time-restricted feeding improves insulin sensitivity, blood pressure, and oxidative stress even without weight loss in men with prediabetes. Cell Metabolism, 27(6), 1212–1221.e3.

Watson, S. L., Weeks, B. K., Weis, L. J., Horan, S. A., & Beck, B. R. (2018). High-intensity resistance and impact training improves bone mineral density and physical function in postmenopausal women with osteopenia and osteoporosis: The LIFTMOR randomized controlled trial. Journal of Bone and Mineral Research, 33(2), 211–220.