Disease Proof

Slow metabolism linked to longevity

Clock. Flickr: macinateWhen we use the word “metabolism,” we are usually referring to resting metabolic rate, which is the amount of energy (calories) that the body requires per day for its basic functions at rest.  Most people believe that it is desirable to raise their metabolism, because they will burn more calories and consequently lose weight.  Having a slightly lower resting metabolic rate is thought to predispose some individuals to weight gain, especially in the obesogenic food environment that we live in.1,2  However,  there are unfavorable consequences to running your body at faster than normal speed, and raising your metabolism is not the key to weight loss.

Toxic byproducts of metabolism and biological aging

The chemical reactions of normal everyday physiology produce byproducts.  In particular, cellular energy production produces reactive oxygen species as a byproduct, which can damage DNA, proteins, and lipids.  Although we have natural antioxidant defenses, oxidative damage can still occur, especially if we don’t take in adequate antioxidants from our diet.3  Oxidative damage accelerates aging.

Aging here refers to biological aging – the progressive decline in the efficiency of the body’s physiological functions over time. This leads to tissue and organ damage, and increased risk of chronic disease and death. 

Why do our bodies age?  It is a combination of factors.   One, the accumulation of oxidative damage over time damages the body’s tissues, leading to accelerated aging.4,5 And two, just the rate of living slowly wears out our cellular machinery, so if we function at a faster rate – i.e. a faster metabolism – the body will “wear out” more quickly.  In animals, energy expenditure is indeed inversely related to lifespan, supporting this.6   Though both these mechanisms of aging are related, as a faster metabolic rate means faster energy turnover and greater production of free radicals, leading to increased oxidative damage. 

Metabolic rate and lifespan

A study on thyroid function published last year further supported the idea that a slower metabolic rate could prolong lifespan.  Now, a new study has measured resting metabolic rate directly and come to the same conclusion.  Metabolic rate was measured by two different methods at the start of the study.  Subjects were followed for 11-15 years, and deaths from natural causes were recorded.  For each 100 calorie increase in 24-hour resting metabolic rate, the risk of natural mortality increased by 25-29%.  These results strongly support the hypothesis that a slow metabolic rate promotes longevity.7

Do we have any control over our resting metabolic rate? How can we slow it down?

Resting metabolic rate is largely genetically determined, but our calorie intake has an effect as well.8  Caloric restriction and negative energy balance have been shown to reduce resting metabolic rate, and in contrast overeating increases resting metabolic rate.9,10  Furthermore, caloric restriction has been consistently shown to prolong maximal lifespan by up to 60% in animals.11  My findings have demonstrated that an optimal micronutrient intake reduces the desire for calories and reduces body temperature and white blood cell counts. This means that if follow a high-nutrient eating style that reduces calorie intake while meeting micronutrient demands, we can reduce our resting metabolic rate and potentially increase our longevity potential dramatically.

Keep in mind that although exercise raises total calorie expenditure, it does not raise the body’s basal metabolism. Exercise is the only safe way to “raise metabolism” because it activates the peripheral tissues to utilize more calories and also increases muscle mass which in turn increases total calorie expenditure.12  Plus, exercise promotes longevity.13  

The goal here is to eat so healthy that it reduces your desire to overeat and reduces your metabolism slowly, so you can comfortably desire less food, though not get too thin.  My nutritarian recommendations actually makes you more satisfied with less food, and actually gives the ability to enjoy food more without overeating. 

So this new study supports what I have said previously: having a fast metabolism does not mean that you are healthier – in fact, it probably means that you are aging more quickly.  Instead of trying to increase your metabolism with the goal of losing weight, try to slow your metabolism with a low-calorie, high-nutrient diet for a longer, healthier life.

 

 

References:

1. Astrup A, Gotzsche PC, van de Werken K, et al: Meta-analysis of resting metabolic rate in formerly obese subjects. Am J Clin Nutr 1999;69:1117-1122.

2. Ravussin E, Lillioja S, Knowler WC, et al: Reduced rate of energy expenditure as a risk factor for body-weight gain. N Engl J Med 1988;318:467-472.

3. Joseph JA, Denisova N, Fisher D, et al: Age-related neurodegeneration and oxidative stress: putative nutritional intervention. Neurol Clin 1998;16:747-755.

4. Hulbert AJ, Pamplona R, Buffenstein R, et al: Life and death: metabolic rate, membrane composition, and life span of animals. Physiol Rev 2007;87:1175-1213.

5. Farooqui T, Farooqui AA: Aging: an important factor for the pathogenesis of neurodegenerative diseases. Mech Ageing Dev 2009;130:203-215.

6. Speakman JR, Selman C, McLaren JS, et al: Living fast, dying when? The link between aging and energetics. J Nutr 2002;132:1583S-1597S.

7. Jumpertz R, Hanson RL, Sievers ML, et al: Higher Energy Expenditure in Humans Predicts Natural Mortality. J Clin Endocrinol Metab 2011.

8. Bouchard C, Tremblay A, Nadeau A, et al: Genetic effect in resting and exercise metabolic rates. Metabolism 1989;38:364-370.

9. Martin CK, Heilbronn LK, de Jonge L, et al: Effect of calorie restriction on resting metabolic rate and spontaneous physical activity. Obesity 2007;15:2964-2973.

10. Roberts SB, Fuss P, Evans WJ, et al: Energy expenditure, aging and body composition. J Nutr 1993;123:474-480.

11. Fontana L: The scientific basis of caloric restriction leading to longer life. Curr Opin Gastroenterol 2009;25:144-150.

12. Broeder CE, Burrhus KA, Svanevik LS, et al: The effects of aerobic fitness on resting metabolic rate. Am J Clin Nutr 1992;55:795-801.

13. Manini TM, Everhart JE, Patel KV, et al: Daily activity energy expenditure and mortality among older adults. JAMA 2006;296:171-179.

 

 

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Comments (20) Read through and enter the discussion with the form at the end
Mia Z - June 3, 2011 10:19 AM

You guys have brought up this topic before, but I'm glad to see it come back as a reminder. I think in addition, it should be mentioned that eating fewer times a day is another factor, not just caloric intake... if I recall correctly :)

mike crosby - June 3, 2011 11:16 AM

obesogenic-a recent medical term for factors tending to make individuals fat

Every time I use a big word my tells me to give her a dime. That's a really cool word, I'm going to have to use that one on her tonight.

Thank you for your blog Dr Fuhrman--without a doubt you're my hero!

Peter - June 3, 2011 11:43 AM

Dr. Fuhrman, thank you for another great article.

I think you might want to rewrite this one sentence:

In animals, energy expenditure is indeed inversely related to lifespan, supporting this.

I think it is written in a confusing way.

Thank you,
Peter

StephenMarkTurner - June 3, 2011 1:00 PM

I agree with Mike, 'obesogenic' is a completely cool word.

One question that I have is whether it is possible to carry a little muscle, but still have a lower metabolism.

Regards,
Steve

P K - June 5, 2011 1:39 AM

I don't understand - exercise promotes longevity, even though it raises your metabolism?

Mark Osborne - June 6, 2011 3:12 PM

Exercise's impact on basil metabolism?

It is surprising that that exercise does not have any affect on basal metabolism. Regular exercise ultimately leads to a lower resting heart rate and improved muscle efficiency due to increased mitochondrial efficiency.
And exercise, especially weight training, can increase muscle masss. Those all sound like things that might have some impact your metabolism.

Whatever the case exercise has been shown to not just increase lifespan but more importantly it improves the quality of life by offsetting the decline typically seen with aging.

Zach - June 7, 2011 7:40 AM

I also am a little puzzled by Dr. Fuhrman's comments about exercise in this article. As a certified personal trainer, I was taught that muscle mass burns more calories ALL THE TIME than other body mass, so adding muscle is effective for weight loss BECAUSE it raises your BMR. Are you suggesting that the manner in which muscle burns calories is less damaging than the way that other tissues burn calories, or are you just trying to avoid discouraging exercise (even though it may in fact promote aging) due to it's benefits in fighting osteoporosis, preventing muscle atrophy, and improving quality of life?

Jerry Amos - June 7, 2011 3:42 PM

COQ10 raises the metabolism of wire worms and reduces their life span...according to evidence based research, I may have the reference somewhere on one of my pc's.

Do note in the scientific book "The China Study" prof. T. Colin Campbell reports that reducing animal protein levels to 5% of calories improved health and life span in a controlled study of rats. They were allowed to eat as much as they wanted and at the end of 100 weeks they were all in fine shape, full glossy coats, ... Rats on 20% animal protein were all dead...

jock rogers - June 7, 2011 4:03 PM

When I was about 50 lbs lighter and doing long distance running, my resting pulse was consistently in the mid 40s. Now that I'm out of shape and overweight, it often is in the 70s and 80s. I think there's a lesson here.

I'm finding that as I'm working with Dr. Fuhrman's eating plans, I'm starting to have less food urges, more energy, and have been getting out for exercise. (Fast walking for an hour every day.)

I know the ticker will start to slow down. Many thanks for your help.

Scott D - June 7, 2011 4:31 PM

I also felt the same thing as Zach's comments above. There seems to possibly be a contradiction that needs to just be explained a bit further.

Adding muscle mass and regular exercise has health promoting benefits of course but it was my understanding that increased muscle mass burns more calories, thereby increasing your daily caloric needs and increasing your RMR (resting metabolic rate).

A quick search turned up this study http://www.ncbi.nlm.nih.gov/pubmed/3492457 which concluded by saying "...The results showed that exercise-training induced a significant rise in RMR ..."

I think the athletes here would like some clarification on this.

Mike Maybury - June 7, 2011 4:48 PM

Mia mentioned fewer meals. I can confirm that I have had two meals a day for over 60 years.
At 76, all my adult life I've eaten wholefood vegetarian food. Typically vegetables and fruit comprised 75% of the diet. In earlier life I did not pay much attention to exercise, but chose work and recreation that was probably sufficient. Now retired, in the summer I can walk on a shingle beach up to 6 hours, for the benefit of the exercise, and possibly a little too much sun. Dancing for up to 20 hours weekly was also part of my lifestyle.
'Flu only once in those adult years and 1 cold in the last five years, no aches and pains and ability to do anthing that I want- (I don't want to run for miles on roads!)seems to show that a simple lifestyle is worth while. Life has been great fun , particularly since age 40,and my health compares very well with my peers and siblings. I think that I'll now aim for age 100, as long as I keep well!

Rob Lovegreen - June 7, 2011 5:05 PM

Thanks so much Dr.Fuhrman. Great Information. Another reason to stay nutritarian in my eating endeavors. I'm re-posting this to Facebook. Blessings -Rob

Dan - June 7, 2011 5:48 PM

It seems that those on a raw food diet (80/10/10 specifically) have to eat many more calories (often 3000+) in order not to lose too much weight, even though activity levels may be low.

Are they doing themselves harm by overeating on calories? It seems to be the opposite of calorie restriction.

ruth - June 7, 2011 6:42 PM

I've recently been put on thyroid medication and I'm wondering if the nutritarian way of eating may reduce (or eliminate) my need for thyroid meds. Reading about low metabolic rate made me even more keen to stop taking them.

Claudia - June 7, 2011 7:06 PM

Mark and Zach:

What Dr. Fuhrman has explained in the past is that exercise does not increase core (central nervous system) metabolism, rather it increases peripheral utilization of energy or peripheral metabolic need. It is the core metabolism that is favorable to be slower in terms of longevity. So, exercise does not adversely effect your core metabolism. It does however, increase your peripheral metabolism, which is conducive to weight loss, and achieving and maintaining an ideal weight.

I am not sure, but I think that the resting heart rate is related to core metabolism, such that a fit person with a slower heart rate would have a slower core metabolism. It means that the fit person has a body that doesn't have to expend as much energy just to breathe and exist. In other words, they are functioning efficiently. A fit person who has developed an exercise tolerance, is able to handle the basics of living and breathing with less energy expenditure than an out of shape person.

Deana Ferreri, Ph.D. - June 8, 2011 8:44 AM

Re: muscle mass

What Claudia said is correct. Sometimes it can be confusing because of the meaning of the terms "resting metabolic rate"- if we are talking about calories burned at rest, yes that increases with muscle mass. Often, resting metabolic rate is calculated per unit of lean body mass, in which case an increase in lean body mass would not change RMR. Also, when we are talking about the body's basal metabolism, which is controlled by the thyroid, this does not seem to change with changes in muscle mass.

Zach - June 8, 2011 1:18 PM

Glad to hear. Now I can continue my (nutritarian, of course) body building without worrying about seriously harming my longevity. Cheers!

John-Allen Mollenhauer - June 9, 2011 11:17 AM

Of course there are also other points of reference on the Rate of Living theory; there is the perspective of metabolism as it relates to nutrition and also the rate at which we wear our bodies down by stress - over activity and lack of vital energy recuperation in relative balance with expenditure; this is rate of living from a lifestyle point of view, which is a series of life dynamics that need to be managed, in addition nutrition alone.

susan - July 17, 2011 11:02 AM

I have Dr. Fuhrman's Eat To Live Book, and am starting to put the diet into practise. I am amazed by some of the weightloss stories I have seen in there! Reading this about how low calorie, but high nutrient eating slows down the metabolism though, I'm wondering, how are these people losing the weight? I guess I'm just confused about that part. Also, in Eat To Live, it says that calorie restriction has very little effect on metabolic rate!

sue - July 23, 2011 12:05 PM

I sure wish Dr Fuhrman would chime in here and clear up the confusion! I'm confused, because I don't know how you lose weight if your metabolism gets too slow, and mine is already slow.

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