Though a bane for dieters, a slower metabolism may actually be a good thing.
The Benefits of Calorie Restriction for Longevity
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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Though a bane for dieters, a slower metabolism may actually be a good thing. We’ve known for more than a century that calorie restriction can increase the lifespan of animals, and the metabolic slowdown may be the mechanism. That could be why the tortoise lives 10 times longer than the hare. Rabbits can live 10 to 20 years, whereas “Harriet,” a tortoise evidently collected from the Galapagos by none other than Charles Darwin himself in the 1830s, lived until 2006. Slow and steady may win the race.
One of the ways your body lowers your resting metabolic rate is by creating cleaner-burning, more efficient mitochondria, the power plants that fuel our cells. It’s like your body passes its own fuel-efficiency standards. These new mitochondria create the same energy with less oxygen, and produce less free radical “exhaust.” After all, your body is afraid famine is afoot, and so, it is trying to conserve as much energy as it can.
The largest caloric restriction trial to date indeed found both metabolic slowing and a reduction in free radical-induced oxidative stress—both of which may slow the rate of aging. The flame that burns twice as bright burns half as long. But whether this will result in greater human longevity is an unanswered question. Caloric restriction is often said to extend the lifespan of “every species studied.” But that isn’t even true of all strains within a single species. Some scientists don’t think calorie restriction will improve human longevity at all; others suggest a 20 percent calorie restriction starting at age 25 and sustained for 52 years could add 5 years onto your life. Either way, the reduced oxidative stress would be expected to improve our healthspan.
Members of the Calorie Restriction Society, self-styled CRONies (for Calorie-Restricted Optimal Nutrition), appear to be in excellent health, but they’re a rather unique self-selected bunch of individuals. You don’t really know until you put it to the test. Enter the CALERIE study, the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy, the first clinical trial to test the effects of caloric restriction.
Hundreds of non-obese men and women were randomized to two years of 25 percent calorie restriction. They only ended up achieving half that but lost about 18 pounds and three inches off their waists, wiping out more than half of their visceral abdominal fat. That translated into significant improvements in cholesterol levels, triglycerides, insulin sensitivity, and blood pressures. Eighty percent of those who were overweight when they started were normal weight by the end, compared to a 27-percent increase in those who became overweight in the control group.
In the famous Minnesota Starvation Study that used conscientious objectors as guinea pigs during World War II, the study subjects suffered both physically and psychologically, experiencing depression, irritability, and loss of libido. The subjects started out lean, though, and had their calorie intake cut in half. The CALERIE study ended up being four times less restrictive, only about 12 percent below baseline calorie intake, and enrolled normal-weight individuals, which in the U.S. these days means overweight, on average. As such, the CALERIE subjects experienced nothing but positive quality-of-life benefits, with significant improvements in mood, general health, sex drive, and sleep. They only ended up eating about 300 fewer calories than they were eating at baseline. So, they got all these benefits—the physiological benefits, the psychological benefits—all from only cutting about a snack-sized bag of chips worth of calories from their daily diets.
What happened at the end of the trial, though? In the Minnesota Starvation Study and calorie deprivation experiments done on Army Rangers, as soon as subjects were released from restriction, they tended to rapidly regain the weight, and sometimes even more. The leaner they started out, the more their bodies seemed to drive them to overeat to pack back on the extra body fat. In contrast, after the completion of the CALERIE study, even though their metabolism was slowed, they retained about 50 percent of the weight loss two years later. They must have acquired new eating attitudes and behaviors that allowed them to keep their weight down. After extended calorie restriction, for example, cravings for sugary, fatty, and junky foods may actually go down.
Please consider volunteering to help out on the site.
- Hall KD. Metabolic Adaptations to Weight Loss. Obesity (Silver Spring). 2018;26(5):790-791.
- Osborne TB, Mendel LB, Ferry EL. The effect of retardation of growth upon the breeding period and duration of life of rats. Science. 1917;45(1160):294-5.
- Redman LM, Smith SR, Burton JH, Martin CK, Il'yasova D, Ravussin E. Metabolic Slowing and Reduced Oxidative Damage with Sustained Caloric Restriction Support the Rate of Living and Oxidative Damage Theories of Aging. Cell Metab. 2018;27(4):805-815.e4.
- The Animal Ageing and Longevity Database: AnAge entry for Lepus europaeus. Human Ageing Genomic Resources.
- The Animal Ageing and Longevity Database: AnAge entry for Chelonoidis nigra. Human Ageing Genomic Resources.
- Civitarese AE, Carling S, Heilbronn LK, et al. Calorie restriction increases muscle mitochondrial biogenesis in healthy humans. PLoS Med. 2007;4(3):e76.
- Bourzac K. Interventions: live long and prosper. Nature. 2012;492(7427):S18-20.
- Rebrin I, Forster MJ, Sohal RS. Association between life-span extension by caloric restriction and thiol redox state in two different strains of mice. Free Radic Biol Med. 2011;51(1):225-33.
- Bourg EL, Redman LM. Do‐It‐Yourself Calorie Restriction: The Risks of Simplistically Translating Findings in Animal Models to Humans. Bioessays. 2018;40(9):1-2
- Dai DF, Chiao YA, Marcinek DJ, Szeto HH, Rabinovitch PS. Mitochondrial oxidative stress in aging and healthspan. Longev Healthspan. 2014;3:6.
- Anderson RM, Le Couteur DG, de Cabo R. Caloric Restriction Research: New Perspectives on the Biology of Aging. J Gerontol A Biol Sci Med Sci. 2018;73(1):1–3.
- Most J, Gilmore LA, Smith SR, Han H, Ravussin E, Redman LM. Significant improvement in cardiometabolic health in healthy nonobese individuals during caloric restriction-induced weight loss and weight loss maintenance. Am J Physiol Endocrinol Metab. 2018;314(4):E396–E405.
- Ravussin E, Redman LM, Rochon J, et al. A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity. J Gerontol A Biol Sci Med Sci. 2015 Sep;70(9):1097-104.
- Das SK, Roberts SB, Bhapkar MV, et al. Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-y randomized controlled trial of calorie restriction in nonobese humans. Am J Clin Nutr. 2017;105(4):913-927.
- Kalm LM, Semba RD. They starved so that others be better fed: remembering Ancel Keys and the Minnesota experiment. J Nutr. 2005;135(6):1347-52.
- Dirks AJ, Leeuwenburgh C. Caloric restriction in humans: potential pitfalls and health concerns. Mech Ageing Dev. 2006;127(1):1-7.
- Martin CK, Bhapkar M, Pittas AG, et al. Effect of Calorie Restriction on Mood, Quality of Life, Sleep, and Sexual Function in Healthy Nonobese Adults: The CALERIE 2 Randomized Clinical Trial. JAMA Intern Med. 2016;176(6):743–752.
- Franklin JC, Schiele BC, Brozek J, Keys A. Observations on human behavior in experimental semistarvation and rehabilitation. J Clin Psychol. 1948;4(1):28-45.
- Friedl KE, Moore RJ, Hoyt RW, Marchitelli LJ, Martinez-lopez LE, Askew EW. Endocrine markers of semistarvation in healthy lean men in a multistressor environment. J Appl Physiol. 2000;88(5):1820-30.
- Dulloo AG, Jacquet J, Montani JP. How dieting makes some fatter: from a perspective of human body composition autoregulation. Proc Nutr Soc. 2012;71(3):379-89.
- Kahathuduwa CN, Binks M, Martin CK, Dawson JA. Extended calorie restriction suppresses overall and specific food cravings: a systematic review and a meta-analysis. Obes Rev. 2017;18(10):1122-35.
- Marlatt KL, Redman LM, Burton JH, Martin CK, Ravussin E. Persistence of weight loss and acquired behaviors 2 y after stopping a 2-y calorie restriction intervention. Am J Clin Nutr. 2017;105(4):928–935.
Image credit: Matthew Bennett via unsplash. Image has been modified.
Motion graphics by Avocado Video
Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Though a bane for dieters, a slower metabolism may actually be a good thing. We’ve known for more than a century that calorie restriction can increase the lifespan of animals, and the metabolic slowdown may be the mechanism. That could be why the tortoise lives 10 times longer than the hare. Rabbits can live 10 to 20 years, whereas “Harriet,” a tortoise evidently collected from the Galapagos by none other than Charles Darwin himself in the 1830s, lived until 2006. Slow and steady may win the race.
One of the ways your body lowers your resting metabolic rate is by creating cleaner-burning, more efficient mitochondria, the power plants that fuel our cells. It’s like your body passes its own fuel-efficiency standards. These new mitochondria create the same energy with less oxygen, and produce less free radical “exhaust.” After all, your body is afraid famine is afoot, and so, it is trying to conserve as much energy as it can.
The largest caloric restriction trial to date indeed found both metabolic slowing and a reduction in free radical-induced oxidative stress—both of which may slow the rate of aging. The flame that burns twice as bright burns half as long. But whether this will result in greater human longevity is an unanswered question. Caloric restriction is often said to extend the lifespan of “every species studied.” But that isn’t even true of all strains within a single species. Some scientists don’t think calorie restriction will improve human longevity at all; others suggest a 20 percent calorie restriction starting at age 25 and sustained for 52 years could add 5 years onto your life. Either way, the reduced oxidative stress would be expected to improve our healthspan.
Members of the Calorie Restriction Society, self-styled CRONies (for Calorie-Restricted Optimal Nutrition), appear to be in excellent health, but they’re a rather unique self-selected bunch of individuals. You don’t really know until you put it to the test. Enter the CALERIE study, the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy, the first clinical trial to test the effects of caloric restriction.
Hundreds of non-obese men and women were randomized to two years of 25 percent calorie restriction. They only ended up achieving half that but lost about 18 pounds and three inches off their waists, wiping out more than half of their visceral abdominal fat. That translated into significant improvements in cholesterol levels, triglycerides, insulin sensitivity, and blood pressures. Eighty percent of those who were overweight when they started were normal weight by the end, compared to a 27-percent increase in those who became overweight in the control group.
In the famous Minnesota Starvation Study that used conscientious objectors as guinea pigs during World War II, the study subjects suffered both physically and psychologically, experiencing depression, irritability, and loss of libido. The subjects started out lean, though, and had their calorie intake cut in half. The CALERIE study ended up being four times less restrictive, only about 12 percent below baseline calorie intake, and enrolled normal-weight individuals, which in the U.S. these days means overweight, on average. As such, the CALERIE subjects experienced nothing but positive quality-of-life benefits, with significant improvements in mood, general health, sex drive, and sleep. They only ended up eating about 300 fewer calories than they were eating at baseline. So, they got all these benefits—the physiological benefits, the psychological benefits—all from only cutting about a snack-sized bag of chips worth of calories from their daily diets.
What happened at the end of the trial, though? In the Minnesota Starvation Study and calorie deprivation experiments done on Army Rangers, as soon as subjects were released from restriction, they tended to rapidly regain the weight, and sometimes even more. The leaner they started out, the more their bodies seemed to drive them to overeat to pack back on the extra body fat. In contrast, after the completion of the CALERIE study, even though their metabolism was slowed, they retained about 50 percent of the weight loss two years later. They must have acquired new eating attitudes and behaviors that allowed them to keep their weight down. After extended calorie restriction, for example, cravings for sugary, fatty, and junky foods may actually go down.
Please consider volunteering to help out on the site.
- Hall KD. Metabolic Adaptations to Weight Loss. Obesity (Silver Spring). 2018;26(5):790-791.
- Osborne TB, Mendel LB, Ferry EL. The effect of retardation of growth upon the breeding period and duration of life of rats. Science. 1917;45(1160):294-5.
- Redman LM, Smith SR, Burton JH, Martin CK, Il'yasova D, Ravussin E. Metabolic Slowing and Reduced Oxidative Damage with Sustained Caloric Restriction Support the Rate of Living and Oxidative Damage Theories of Aging. Cell Metab. 2018;27(4):805-815.e4.
- The Animal Ageing and Longevity Database: AnAge entry for Lepus europaeus. Human Ageing Genomic Resources.
- The Animal Ageing and Longevity Database: AnAge entry for Chelonoidis nigra. Human Ageing Genomic Resources.
- Civitarese AE, Carling S, Heilbronn LK, et al. Calorie restriction increases muscle mitochondrial biogenesis in healthy humans. PLoS Med. 2007;4(3):e76.
- Bourzac K. Interventions: live long and prosper. Nature. 2012;492(7427):S18-20.
- Rebrin I, Forster MJ, Sohal RS. Association between life-span extension by caloric restriction and thiol redox state in two different strains of mice. Free Radic Biol Med. 2011;51(1):225-33.
- Bourg EL, Redman LM. Do‐It‐Yourself Calorie Restriction: The Risks of Simplistically Translating Findings in Animal Models to Humans. Bioessays. 2018;40(9):1-2
- Dai DF, Chiao YA, Marcinek DJ, Szeto HH, Rabinovitch PS. Mitochondrial oxidative stress in aging and healthspan. Longev Healthspan. 2014;3:6.
- Anderson RM, Le Couteur DG, de Cabo R. Caloric Restriction Research: New Perspectives on the Biology of Aging. J Gerontol A Biol Sci Med Sci. 2018;73(1):1–3.
- Most J, Gilmore LA, Smith SR, Han H, Ravussin E, Redman LM. Significant improvement in cardiometabolic health in healthy nonobese individuals during caloric restriction-induced weight loss and weight loss maintenance. Am J Physiol Endocrinol Metab. 2018;314(4):E396–E405.
- Ravussin E, Redman LM, Rochon J, et al. A 2-Year Randomized Controlled Trial of Human Caloric Restriction: Feasibility and Effects on Predictors of Health Span and Longevity. J Gerontol A Biol Sci Med Sci. 2015 Sep;70(9):1097-104.
- Das SK, Roberts SB, Bhapkar MV, et al. Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-y randomized controlled trial of calorie restriction in nonobese humans. Am J Clin Nutr. 2017;105(4):913-927.
- Kalm LM, Semba RD. They starved so that others be better fed: remembering Ancel Keys and the Minnesota experiment. J Nutr. 2005;135(6):1347-52.
- Dirks AJ, Leeuwenburgh C. Caloric restriction in humans: potential pitfalls and health concerns. Mech Ageing Dev. 2006;127(1):1-7.
- Martin CK, Bhapkar M, Pittas AG, et al. Effect of Calorie Restriction on Mood, Quality of Life, Sleep, and Sexual Function in Healthy Nonobese Adults: The CALERIE 2 Randomized Clinical Trial. JAMA Intern Med. 2016;176(6):743–752.
- Franklin JC, Schiele BC, Brozek J, Keys A. Observations on human behavior in experimental semistarvation and rehabilitation. J Clin Psychol. 1948;4(1):28-45.
- Friedl KE, Moore RJ, Hoyt RW, Marchitelli LJ, Martinez-lopez LE, Askew EW. Endocrine markers of semistarvation in healthy lean men in a multistressor environment. J Appl Physiol. 2000;88(5):1820-30.
- Dulloo AG, Jacquet J, Montani JP. How dieting makes some fatter: from a perspective of human body composition autoregulation. Proc Nutr Soc. 2012;71(3):379-89.
- Kahathuduwa CN, Binks M, Martin CK, Dawson JA. Extended calorie restriction suppresses overall and specific food cravings: a systematic review and a meta-analysis. Obes Rev. 2017;18(10):1122-35.
- Marlatt KL, Redman LM, Burton JH, Martin CK, Ravussin E. Persistence of weight loss and acquired behaviors 2 y after stopping a 2-y calorie restriction intervention. Am J Clin Nutr. 2017;105(4):928–935.
Image credit: Matthew Bennett via unsplash. Image has been modified.
Motion graphics by Avocado Video
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Title
The Benefits of Calorie Restriction for Longevity
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
This is part of my video series on calorie restriction, intermittent fasting, and time-restricted eating. Next up is Potential Pitfalls of Calorie Restriction.
The rest coming out over the next few months are:
- Benefits of Fasting for Weight Loss Put to the Test
- Is Fasting Beneficial for Weight Loss?
- Is Fasting for Weight Loss Safe?
- Alternate-Day Intermittent Fasting Put to the Test
- Is Alternate-Day Intermittent Fasting Safe?
- Does Intermittent Fasting Increase Human Life Expectancy?
- The 5:2 Diet and the Fasting-Mimicking Diet Put to the Test
- Time-Restricted Eating Put to the Test
- The Benefits of Early Time-Restricted Eating
You can also watch them all on a digital download.
All of my newest videos on longevity can be found on the topic page.
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