The Facts About Weight Gain and Aging

As we age, the body undergoes predictable physiologic changes that affect metabolism, hormone signaling, muscle mass, and fat distribution. One of the most significant contributors to age-related weight gain is hormonal decline. Over time, hormone production decreases, and target tissues may become less responsive to hormonal signals, making weight management increasingly difficult.

Hormones such as testosterone and estrogen play central roles in regulating body composition, energy expenditure, insulin sensitivity, and muscle preservation. As these hormones decline with age, many individuals experience increased fat accumulation—particularly visceral (abdominal) fat—along with reduced lean muscle mass, which further slows metabolism (Santoro et al., 2015).

Hormonal Changes and Weight Gain

Aging-related weight gain is not simply a matter of eating more or exercising less. Hormonal shifts alter how the body stores fat, uses energy, and maintains muscle. Lower hormone levels also affect sleep quality, motivation, and recovery—factors that indirectly contribute to weight gain.

Research shows that hormonal decline contributes to:

• Reduced basal metabolic rate

• Increased insulin resistance

• Loss of muscle mass (sarcopenia)

• Increased fat storage, particularly around the abdomen

These changes occur in both men and women, though the hormonal drivers differ.

Effects of Low Testosterone (“Low T”) in Men

As men age, testosterone levels gradually decline—a process commonly referred to as andropause or male hormone decline. Testosterone is critical for maintaining lean muscle mass, regulating fat distribution, supporting insulin sensitivity, and preserving bone density.

When testosterone levels fall, men are more likely to experience:

• Increased body fat, particularly visceral abdominal fat

• Reduced muscle mass and strength

• Decreased energy and stamina

• Irritable or depressed mood

• Joint and back pain

• Difficulty focusing and cognitive fatigue

(Basaria, 2014; Traish et al., 2018)

Low testosterone is strongly associated with metabolic syndrome, insulin resistance, and increased cardiovascular risk. Because muscle tissue is metabolically active, its loss further accelerates fat gain and metabolic slowdown (Kelly & Jones, 2013).

Symptoms of Low Estrogen in Women

Women experience significant hormonal changes during perimenopause and menopause, marked by declining estrogen production from the ovaries. Estrogen plays a vital role in regulating fat distribution, muscle tone, insulin sensitivity, and energy utilization.

As estrogen levels decline, women may experience:

• Increased abdominal fat accumulation

• Hot flashes and night sweats

• Mood swings and irritability

• Mental fog and reduced concentration

• Sleep disturbances and insomnia

• Decreased muscle tone and strength

(The North American Menopause Society [NAMS], 2022)

Estrogen decline also reduces exercise tolerance, meaning women may fatigue more quickly during physical activity and experience slower recovery. This makes traditional weight-loss strategies less effective and more frustrating during midlife and beyond (Davis et al., 2015).

Why Weight Loss Becomes More Difficult with Age

The combination of hormonal decline, muscle loss, sleep disruption, and insulin resistance creates a metabolic environment that favors fat storage over fat burning. Even with consistent diet and exercise, many men and women find that weight gain continues despite their best efforts.

This is why addressing hormonal balance—not just calories—is critical when managing age-related weight gain.

How Bioidentical Hormone Replacement Therapy Can Help

Both men and women with hormone deficiencies may benefit significantly from bioidentical hormone replacement therapy (BHRT). Bioidentical hormones are structurally identical to the hormones naturally produced by the body, allowing them to be recognized and utilized more effectively (Stuenkel et al., 2015).

When used appropriately, BHRT may help:

• Improve insulin sensitivity

• Reduce visceral fat accumulation

• Preserve or rebuild lean muscle mass

• Improve energy levels and exercise tolerance

• Support metabolic efficiency

• Improve sleep quality and mood

Restoring estrogen or testosterone to optimal physiologic levels can help re-establish healthier body composition, making weight management more achievable and sustainable (Manson et al., 2017).

Personalized Hormone Optimization at Hormone Treatment Centers

At Hormone Treatment Centers, we recognize that aging-related weight gain is complex and individualized. Our medical team works closely with each patient to develop a customized hormone replacement plan based on:

• Comprehensive lab testing

• Symptom assessment

• Metabolic and cardiovascular risk factors

• Individual response to therapy

Treatment plans are continually monitored and adjusted to optimize blood chemistry, improve metabolic health, and support long-term wellness.

If you’re struggling with unexplained weight gain, fatigue, or changes in body composition, hormone imbalance may be playing a role.

Contact Hormone Treatment Centers today to learn how personalized hormone therapy can help support healthy aging and weight management.

References

Basaria, S. (2014). Male hypogonadism. The Lancet, 383(9924), 1250–1263.
Davis, S. R., et al. (2015). Understanding weight gain at menopause. Climacteric, 18(3), 303–308.
Kelly, D. M., & Jones, T. H. (2013). Testosterone and obesity. Obesity Reviews, 14(7), 581–593.
Manson, J. E., et al. (2017). Menopausal hormone therapy and long-term health outcomes. JAMA, 318(10), 927–938.
Santoro, N., et al. (2015). Menopause and metabolic health. Endocrine Reviews, 36(1), 1–25.
Stuenkel, C. A., et al. (2015). Treatment of menopausal symptoms: Endocrine Society guideline. Journal of Clinical Endocrinology & Metabolism, 100(11), 3975–4011.
The North American Menopause Society. (2022). The 2022 hormone therapy position statement. Menopause, 29(7), 767–794.
Traish, A. M., et al. (2018). Testosterone deficiency and metabolic dysfunction. Current Opinion in Endocrinology, 25(3), 197–203.