Generated Summary
The article discusses a recent study, and subsequent analysis, on the effects of calorie restriction on human lifespan and aging. The primary study, the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE), involved 220 adults who were either assigned to a calorie restriction group (reducing intake by 25% without skipping essential nutrients) or a control group that ate what they wanted for two years. Researchers analyzed blood samples from participants to examine the association between calorie restriction and DNA methylation, which are measures of aging. The study aimed to determine if calorie restriction could slow the aging process and potentially extend lifespan. The CALERIE trial’s approach included a randomized controlled design to investigate the impact of long-term calorie restriction on various health metrics and aging biomarkers. The study’s scope was limited to a specific age range (21-50 years) and a specific level of calorie reduction (25%), examining how the restriction affected DNA methylation markers associated with aging. The analysis explored changes in DNA methylation through the use of epigenetic clocks to measure aging in participants. The findings were then compared to existing research on the effects of calorie restriction in other species.
Key Findings & Statistics
- The CALERIE trial randomized 220 adults aged 21 to 50 years.
- Participants in the calorie restriction group aimed to cut their daily calorie intake by 25%.
- On average, the calorie restriction group reduced their intake by approximately 12%.
- At baseline, participants’ body mass index (BMI) ranged from 22 to 27.9.
- Normal weight is a BMI of 18.5 to 24.9.
- 70% of CALERIE participants were women.
- In 2019, the CALERIE investigators reported that calorie restriction significantly improved multiple cardiometabolic risk factors.
- The improvements included cholesterol levels, blood pressure, C-reactive protein, and glucose tolerance.
- The effect on DunedinPACE represented a 2% to 3% slowing of aging.
- Other studies have found this translates to a 10% to 15% reduction in mortality risk, similar to that of a smoking cessation program.
- Participants maintained an average 10% weight loss during the study.
- Muscle mass accounted for only about 17% of total tissue loss in the calorie restriction group.
- Participants in the calorie restriction group lost more muscle mass than those in the control group.
Other Important Findings
- The study found intriguing clues that reducing calorie intake might slow the aging process.
- Calorie restriction significantly improved multiple cardiometabolic risk factors, including cholesterol levels, blood pressure, C-reactive protein, and glucose tolerance.
- The effect on DunedinPACE, a measure of aging, showed a 2% to 3% slowing of aging.
- The relationship between calorie restriction’s health effects and weight loss is “a big question mark.”
- The CALERIE trial found that calorie restriction “really did improve people’s health in the short term.”
Limitations Noted in the Document
- The study acknowledges that human biology is more complex than that of the animals previously studied.
- The calorie restriction group did not achieve the full 25% reduction in calorie intake, averaging only a 12% reduction.
- The long-term effects of calorie restriction remain uncertain.
- The recently launched CALERIE Legacy Study plans to follow up the CALERIE trial participants for 10 to 15 years to see whether the intervention results in sustained improvements in the hallmarks of aging.
- The study’s primary outcome was not reached.
- The study did not account for all variables, such as the varying responses to calorie restriction among different individuals.
- The study acknowledges that other factors could be at play, such as changes in growth hormone and growth, resting metabolic rate, and core temperature.
- One of the issues highlighted in the document is that the long-term effects of calorie restriction are unknown.
Conclusion
The study provides evidence suggesting that calorie restriction may slow aging in humans. The CALERIE trial, a randomized study involving 220 adults, explored the effects of reducing calorie intake on lifespan and aging. The research revealed that although the full 25% calorie reduction goal was not achieved, the participants who restricted their caloric intake showed promising results. The analysis of DNA methylation data, using epigenetic clocks, indicated a slowing of the aging process. Despite these positive outcomes, the study’s authors emphasize that the long-term effects of calorie restriction require further investigation. The findings contribute to the understanding of the connection between diet and aging, indicating a potential for calorie restriction to influence the aging process at the molecular level. Key insights from the study suggest that calorie restriction improves health, as reported in previous studies. The study also acknowledges the need for functional measurements of cognition and muscle function to learn more. The study also notes that weight loss could be part of the game. The researchers also emphasize the need for further research, including the CALERIE Legacy Study, which will follow participants for 10 to 15 years to assess the sustained impacts of calorie restriction. The authors highlight that there are still unanswered questions. Further research is needed to understand the long-term impacts, and the potential for intermittent fasting to yield similar results. The conclusion is that the CALERIE findings are not enough to motivate the author to try the caloric restriction lifestyle.