16:8 Fasting Reduces Body Fat and Visceral Fat in Older Men — While Preserving Muscle Mass: What the Research Shows

Medical disclaimer: This article summarises published research for informational purposes only. It is not medical advice and is not a substitute for guidance from a qualified health professional. Always consult your doctor before starting any fasting protocol, especially if you have an existing health condition or take medication.

Study at a Glance

What This Study Looked At

One of the most common concerns about intermittent fasting in older adults is muscle loss. As people age, sarcopenia — the gradual loss of skeletal muscle mass and strength — becomes a significant health risk, increasing the chance of falls, fractures, metabolic disease, and loss of independence. If fasting accelerates muscle loss in older adults, the risk-to-benefit calculation changes entirely.

This Polish randomized controlled trial set out to test whether time-restricted eating could reduce body fat and visceral fat in overweight men aged 65–74 — while specifically examining whether skeletal muscle mass would be protected or harmed. The study used a standard 16:8 protocol and tested it over six weeks against a control group maintaining normal eating habits.

Who Was Studied

Participant profile: Early elderly men aged 65–74 years, classified as overweight. All participants were healthy non-smokers with no chronic conditions that would confound body composition measurements. Participants were randomized into the two groups at baseline.

How the 16:8 protocol worked in this study: Participants in the TRE group abstained from all calorie-containing food and beverages for exactly 16 hours each day, from 8pm to 12pm the following day. Their entire food intake was confined to a daily 8-hour eating window (noon to 8pm). No specific dietary advice was given about what to eat during the eating window — the intervention was purely about timing.

What the Researchers Found

Body Weight

• The TRE group lost an average of 1.92 kg (95% CI: 1.14–2.70 kg) compared to the control group over six weeks
• This weight loss was achieved without any caloric restriction advice — simply shifting the timing of when food was eaten
• The result was statistically significant

Visceral Fat Mass

• Visceral fat — the deep abdominal fat that surrounds internal organs and is most strongly linked to cardiovascular and metabolic disease — decreased by 0.64 litres (95% CI: 0.46–0.82 L) in the TRE group
• Visceral fat reduction is considered more clinically meaningful than total weight loss, as this fat type drives insulin resistance, inflammation, and cardiovascular risk

Waist Circumference

• Waist circumference decreased by 3.11 cm (95% CI: 1.89–4.33 cm) in the TRE group
• This reflects both the visceral fat reduction and changes in overall abdominal fat distribution

What Did Not Change

• Skeletal muscle mass: No significant change in either group. The TRE protocol did not cause muscle loss in older men over the 6-week period.
• This is the most important finding for older adults concerned about sarcopenia: six weeks of 16:8 fasting reduced fat and visceral fat while fully preserving skeletal muscle.

What the Researchers Concluded

The authors concluded that six weeks of 16:8 time-restricted eating in overweight men aged 65–74 was effective at reducing body weight, visceral fat mass, and waist circumference without causing loss of skeletal muscle mass. They noted high adherence — nearly all participants maintained the protocol throughout the six-week period — suggesting the approach is practically sustainable for this age group.

What This Means If You Fast

• Muscle loss is not inevitable with fasting in older adults. This study provides direct evidence that a standard 16:8 protocol preserves skeletal muscle mass in men aged 65–74 over six weeks. Fear of sarcopenia from fasting is not supported by this data.
• Visceral fat is the real target. Losing 0.64 litres of visceral fat in six weeks — without changing what you eat, only when you eat — is clinically significant. Visceral fat is linked to insulin resistance, cardiovascular risk, and chronic inflammation. Reducing it is one of the most important things an older adult can do for metabolic health.
• 16:8 is manageable at any age. The study found very high adherence among participants in their mid-to-late 60s and early 70s. The common assumption that older adults cannot maintain intermittent fasting is not backed by this evidence.
• Timing alone is a powerful lever. No dietary advice was given in this study — participants simply changed when they ate. The fat and visceral fat reduction seen here came entirely from the timing shift, not caloric restriction. This makes the 16:8 protocol accessible to older adults who may struggle with traditional dieting.
• The eating window placement matters. A 12pm–8pm eating window aligns with typical lunch and dinner timing, making it socially practical for older adults and easier to maintain long-term than early time-restricted eating protocols.

Study Limitations

• Small sample size (n=46) limits the generalisability of findings and statistical power for detecting smaller effects
• Men only — the results cannot be directly extrapolated to older women, in whom hormonal differences affect fat distribution and muscle metabolism differently
• Six weeks is a short duration — longer-term effects on muscle mass, particularly in the context of age-related sarcopenia, require studies of 3–12 months
• No dietary intake was recorded — we do not know whether the TRE group spontaneously reduced calories or changed their food choices during the eating window, which could confound the results
• No measurement of grip strength, gait speed, or functional performance — outcomes directly relevant to sarcopenia and falls risk in older adults
• Polish overweight men aged 65–74 may not represent other ethnicities, body compositions, or older age groups (75+)
• Control group received no intervention — the motivation and attention effects of participating in a study may have influenced TRE group outcomes

Source

Domaszewski, P., Konieczny, M., Pakosz, P., Bączkowicz, D., & Sadowska-Krępa, E. (2022). Effect of a six-week times restricted eating intervention on the body composition in early elderly men with overweight. Scientific Reports, 12(1), 10175. PMID: 35701451

Frequently Asked Questions

Does intermittent fasting cause muscle loss in older adults?

This study found no significant loss of skeletal muscle mass in overweight men aged 65–74 who followed a 16:8 protocol for six weeks. The concern that fasting accelerates sarcopenia in older adults is not supported by these results. Longer studies with larger samples are needed, but the six-week data is reassuring.

How much visceral fat can older adults lose with 16:8 fasting?

In this study, overweight men aged 65–74 lost an average of 0.64 litres of visceral fat over six weeks using only a 16:8 eating window, with no changes to their diet or exercise habits. This is clinically meaningful given how strongly visceral fat is linked to metabolic disease.

How quickly does body weight change on 16:8 fasting for older adults?

In this six-week trial, participants lost an average of 1.92 kg over six weeks — roughly 0.32 kg per week. This rate of weight loss is considered healthy and sustainable, and it was achieved through timing alone rather than caloric restriction.

Is a 12pm–8pm eating window appropriate for older adults?

Yes, and this study suggests it is both effective and achievable. The 12pm–8pm window means skipping breakfast and eating lunch and dinner within an 8-hour window. Nearly all participants in this study maintained the protocol for the full six weeks, indicating strong feasibility in this age group.

Does 16:8 fasting reduce the risk of sarcopenia in older adults?

This study shows that 16:8 fasting does not appear to worsen sarcopenia risk in older men over six weeks — muscle mass was preserved while fat was lost. Whether it actively reduces sarcopenia risk over the longer term — by improving metabolic health and reducing the inflammatory environment in which muscle loss accelerates — requires longer duration studies.

Related Research and Articles

• Does intermittent fasting destroy muscle? Myth vs. fact
• Does intermittent fasting burn muscle?
• How intermittent fasting affects athletic performance
• What is the 16:8 intermittent fasting protocol?
• Can you build muscle while intermittent fasting?
• What happens to your body hour by hour when you fast
• Can intermittent fasting improve insulin sensitivity?

Want the complete guide to fasting? Get Intermittent Fasting in Practice on Amazon — and claim 3 months free on our fasting app at fastinginpractice.com/redeem.