Metabolic rate: the slower, the better

“Metabolism” has become quite a buzzword in our culture. Weight gain or inability to lose weight is often blamed on having a slow metabolism and the prevailing myth is that a faster metabolism is preferable, because it would lead to weight loss. However, having a fast metabolism does not mean that you are healthier – in fact, it may cause you to age more quickly. Many supplements claim to increase your metabolism and promote weight loss, but these are merely stimulants. Instead of trying to increase your metabolism with the goal of losing weight, I say, get your body to run on fewer calories and slow your metabolism for a longer, healthier life.

A study on thyroid function and longevity in families supports my view. This research is part of the Leiden Longevity Study in the Netherlands, in which recruited families had at least two siblings who were alive and had reached age 90 or older – these individuals are referred to as “nonagenarian siblings”.

Since thyroid function is influenced by genetics, and thyroid hormone regulates both basal metabolic rate (energy expenditure at rest with an inactive digestive system) and overall daily energy expenditure [1], the researchers studied thyroid function and longevity in nonagenarian siblings and their family members. [2, 3]

In a study published in 2010, it was established that middle-aged children of nonagenarian siblings had altered thyroid function compared to a control group. They tended to have higher levels of thyrotropin and lower levels of thyroxine (T4) and free triiodothyronine (free T3 – active form of the hormone), indicating lower thyroid function and therefore lower metabolic rate.[2]

A second study measured thyroid hormone levels in nonagenarian siblings and correlations to longevity of their parents. Low thyroid activity in nonagenarian siblings was indeed associated with their parents’ lifespans.[3] The average lifespan of the parents of nonagenarian siblings was an impressive 93 years.

These studies suggest that hereditary factors associated with metabolic rate (thyroid function) are associated with lifespan. This means that taking steps to slow metabolic rate, rather than accelerate it, could be beneficial.

How might a higher metabolic rate promote aging?

One theory is that increased energy expenditure shortens lifespan – that the human body works somewhat like a machine – if it is forced to work too hard and too fast, it will “wear out” more quickly. In a number of small mammal species, daily energy expenditure is indeed inversely related to lifespan, supporting this theory.[4] Accordingly, caloric restriction has been consistently shown to prolong maximal lifespan up to 60% in a variety of species.[5] By reducing calorie intake and still meeting micronutrient demands, daily energy demands are also reduced. Eating predominantly high nutrient, low calorie foods can help to achieve this effect – the body’s micronutrient requirements are satisfied with fewer calories, leading to reduced energy intake and therefore reduced energy demand.

Oxidative damage resulting from the continuous production of reactive oxygen species (as a byproduct of energy metabolism) over time is a related theory of aging.[6] A high nutrient diet would also be effective in this case, since whole plant foods provide both variety and abundance of antioxidants.

The point is we want to eat a diet with excellent micronutrient quality, we will not be hungry as often, we will be comfortable with eating less, and our metabolic rate will slow so that we can eat less and not get too thin.

Don’t buy into the myth – when it comes to metabolism, faster is not better.



1. Kim, B., Thyroid hormone as a determinant of energy expenditure and the basal metabolic rate. Thyroid, 2008. 18(2): p. 141-4.
2. Rozing, M.P., et al., Low serum free triiodothyronine levels mark familial longevity: the Leiden Longevity Study. J Gerontol A Biol Sci Med Sci, 2010. 65(4): p. 365-8.
3. Rozing, M.P., et al., Familial Longevity Is Associated with Decreased Thyroid Function. J Clin Endocrinol Metab, 2010.
4. Speakman, J.R., et al., Living fast, dying when? The link between aging and energetics. J Nutr, 2002. 132(6 Suppl 2): p. 1583S-97S.
5. Fontana, L., The scientific basis of caloric restriction leading to longer life. Curr Opin Gastroenterol, 2009. 25(2): p. 144-50.
6. Hulbert, A.J., et al., Life and death: metabolic rate, membrane composition, and life span of animals. Physiol Rev, 2007. 87(4): p. 1175-213.


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Comments (26) Read through and enter the discussion with the form at the end
Mia Z - September 21, 2010 5:53 PM

Now I'm really curious about whether my 3 days a week of weight-training plus 2 days a week of interval cardio is contributing to a faster metabolism/faster ageing?... But... we already know exercise is healthy, so how can I make a low calorie diet and exercise come together for optimized health and appearance?

Erin - September 21, 2010 10:56 PM

Bummer. I have a fast metabolism.

Laura - September 22, 2010 6:44 AM

I agree with Mia Z. Am I burning my candle too quickly with my exercise routine?

Matt Stone - September 22, 2010 7:31 AM

Then please explain why I receive countless reports from people that chronic health problems disappeared in astonishingly short periods of time when body temperature went from low to the normal 98.6F?

Why is it that Broda Barnes was the most successful physician in history at preventing heart disease, autoimmune disease, and other conditions that a half dozen other popular "alternative" doctors have witnessed using his methods - that is, bringing the body temperature up to the normal 98.6?

I've never seen anyone improve their health by starving themselves of food. Whether your typical centenarian has a "low metabolism" or not is irrelevant, because starving yourself is not likely to take you to a healthy physical state. Rather, it will increase your cortisol levels, increase fat storage enzymes, dissolve lean muscle, increase insulin resistance, compromise immune function, and increase appetite.

At least that's what ETL did for me, as did 80-10-10.

I'm not convinced, to say the least.

Mia Z -

In my experience, weight training and interval cardio does not raise the metabolism, but lowers it (in terms of measuring body temperature).

laura - September 22, 2010 8:54 AM

Dr. Fuhrman says the only way to safely speed metabolism is with exercise. I don't think it raises it enough to negatively affect someone. Other ways of revving up metabolism are not health promoting. These may include using certain medicines (illegal or not) and eating many meals a day.

Vick - September 22, 2010 9:42 AM

So instead of being active and enjoying my life to the fullest, I should opt, for a more sedentary lifestyle, decrease my calorie expenditure, and enjoy a nice long life of sitting on my butt?

I'd rather live my active life, even if it means I die in my 70-80s instead of my 80-90s.

Ginger - September 22, 2010 10:56 AM

Wow! This seems to be a contentious subject. From all my reading of Dr. Fuhrman's writings, I've never gotten the impression that we should starve ourselves or sit on our rears. On the contrary, I can't eat all the food prescribed. It is my understanding that DF plays tennis, does yoga, and runs daily. Correct me if I'm wrong, but that doesn't sound like sitting on one's hind end all day. It is a vibrant, active, health-sustaining lifestyle. Perhaps you don't understand the full picture of his research.

Now for my questions. Is a lower temperature and blood pressure desirable. Mine are both considered low. How low is too low? Is it similar to cholesterol rates, where the lower the BP the better?

Joel Fuhrman, M.D. - September 22, 2010 11:40 AM

That is correct in that exercise is the only safe way to “raise metabolism” because it doesn’t really raise the body’s basal metabolism, but just activates the peripheral tissues to utilize more calories. Exercise prolongs life too. However, exercise taken to extreme, such as marathon running and marathon training is not likely lifespan enhancing.

Eating the right amount of calories and making those calories count regarding micronutrient quality has nothing to do with starving yourself, rather it directs you to the optimal level of nutrient intake, not too much and not too little. But, a nutritarian diet-style enhances digestive and assimilation so that people can maintain a healthy muscle mass and exercise activities on somewhat less calories, without becoming too thin.

Besides the anti-cancer potential the other signs of life enhancement have to do with a lowering of the white blood cell counts in nutritarians.

So Barnes, body temperature treatments with thyroid hormone and Matt Stone’s claims and confusion (trying to raise body temperature in people with normal thyroid function) describe interventions that shorten lifespan and worsen the potential for super longevity. The confusion arises because the Standard diet (SAD) is so atherosclerosis-promoting that using drugs (like thyroid medications) to raise metabolism can induce weight loss and lower the risk of heart disease which only is a benefit (like aspirin is) in a person eating a diet that is atherosclerosis promoting.

Bad_CRC - September 22, 2010 12:28 PM

Matt Stone:

Are you a Crossfitter by any chance? :)

Who is Broda Barnes? Never heard of this person. "Most successful physician in history at preventing heart disease, autoimmune disease, and other conditions" is a pretty tall claim. Did he publish his heart disease reversal outcomes, as Ornish and Esselstyn have (Am J Cardiol, NEJM, Lancet, etc.)?

You personally measured your cortisol, "fat storage enzymes" (which are..?), insulin resistance (what markers?), "immune function" (what is that?), and so on? All that? Before and after your diet changes? You controlled for weight, activity level, and on and on?

Or are you just making **** up?

Jill - September 22, 2010 1:31 PM

This is off topic, but I'd love to hear Disease Proof's thoughts/comments on Bill Clinton discussing his plant-based diet in an effort to prevent heart disease in media interviews this week. Quite a switch from the former lover of Big Macs!

Mia Z - September 22, 2010 3:33 PM

Thanks Dr. Fuhrman, that answers my question perfectly!

Barbara Whitney - September 22, 2010 9:37 PM

My experience has been exactly what Dr. Fuhrman describes, after 4 years following his eating plan. I am fully satisfied with only 1400 calories of nutrient-dense food per day, even though I work out 1-2 hours a day. That is probably half of what I ate in my pre-nutritarian days. I am colder than I used to be and take that as evidence for a lower metabolism.


Kristen - September 24, 2010 2:37 PM

I am training for a half marathon this year, and I am now wondering if that is healthy. I was planning on running a full marathon next year, but I don't want to prematurely age myself or put my body through something that is unhealthy.

In the past I have run up to three miles, but I have found my half marathon training to be one of the best things I have ever done. I have never liked to exercise, but I get such a high from running long distance and I would hate to have to stop!

Does anyone know if Dr. Fuhrman discourages running marathons? I am 5'4" and weight 120 pounds and do not have any health problems.

Kat - September 24, 2010 4:20 PM


All the studies I've seen on endurance athletes have been for people who run marathons or ultra-marathons. If you're a slowish runner, you'll run the half at right around two hours. That's nothing to worry about. I'll bet Dr. Fuhrman's tennis matches go for longer than that.

I also think how taxing the activity is has a lot to do with the analysis. Our bodies were designed to move all day - just not at race pace. In fact, research has shown that sitting all day - even if you exercise regularly - increases early mortality risk. So, I bought a treadmill desk and began walking at 1 mph through the work day. I'm pretty sure that will not shorten my life. It's certainly improved the quality of it.

Pamela - September 25, 2010 10:59 PM


I have discovered in the last year that my entire family - mother, husband, three children and myself all have the supposedly desireable slow metabolism - a.k.a. hypothyroidism. And yes, it was confirmed in each of us using standard thyroid tests. If this means I will live to 100 without proper treatment, forget it.

I choose quality of life, which comes with treating hypothyroidism and increases the metabolism. What's the point of living a long life if you are tired, depressed, overweight, have hair falling out, anxiety attacks, difficulty sleeping, heart palpitations, and 50 other things that are all symptoms of hypothyroidism? I think this research is garbage and gives no consideration to the struggles of those who live with a slow metabolism on a daily basis.

StephenMarkTurner - September 26, 2010 6:33 AM

The number I have heard in the past is an exercise calorie expenditure of around 2000 Cal per week. Exercising more and more will not increase, and will eventually decrease, your mortality protection (statistically anyway). Whether it is the excess exercise, or the increased intake of higher calorie (lower N/C) foods to fuel the work is an interesting question. What if you don't eat SAD diet though. A heavy exercising, but nutritarian, person may be quite a different matter.

Cheers, Steve

Sara - September 26, 2010 7:31 PM

Pamela- He said slow metabolism not hypothyroidism - not the same thing. None of us want to be fat or have our hair fall out or be depressed. A slower metabolism does not mean that your thyroid does not function. Perhaps Dr. Fuhrman or Deana would explain the difference for you.

Kristen - September 27, 2010 10:03 PM

Thank you for the information, Kat! I am sure that it will take me at least two hours to run the half marathon, and I have been training for it with a group of coaches.

I also found an article on this blog about running marathons:

I am going to think twice about running the full marathon next year, however. I can't imagine putting in so much time and effort to eat right and be healthy in other areas of my life just to put undue stress on my body with too much exercise. I think that I am just going to stick with half marathons.

Corrie - October 2, 2010 10:46 PM

I too have hyothyroidism and take eltroxin daily. I would like to know if taking eltroxin is shortening my lifespan by speeding up my metabolism artificially.

I was also curious if thyroid symptoms can be improved by diet - I have not been able to find much information on this except the advice to avoid soy products and certain vegetables.


Ana - October 3, 2010 10:36 PM

I have been diagnosed with Hypothyroidism. I am 26 and have been vegetarian, almost vegan for 2 years. Mi TSH is now around 10 and I have been gaining weight this last year. I am a yoga teacher and have an active lifestyle and I have been feeling sleepy and tired in the last months... What can you do to get my thyroid function back to normal? Should I take medications? Shold I avoid them?

Michael - October 4, 2010 10:45 AM

Hi Ana,

I don't know anything about thyroid issues, but I've had serious bouts of low energy/fatigue due to Vitamin D deficiency. Have you had you levels checked? It might help your energy levels. It certainly helped mine!

Pamela - October 7, 2010 1:44 PM

[Comment deleted due to inappropriate and incorrect dispensing of medical advice]

Keith - October 13, 2010 1:56 PM

I've read some similar studies, and have a few comments.

Health is multi-factoral, meaning.. looking at one study in isolation is not going to be conclusive. As Pamela, above, points out.. there is a lot of data on low thyroid function and ill health.

Not only is there the level of thyroid hormone produced, but its activity level. It can be interfered with by stress (Wilson's Syndrome studies and findings document this stress correlation) and foreign substances like mercury.

Dr. Fuhrman's implication that atherosclerosis, alone, caused by diet is the sole factor in slow metabolism is a bit limited.

Iodine levels (Iodine: Why You Need It, Why You Can't Live Without It - by Brownstein) are another whole area of research to consider.

The point is - there isn't one answer or cause for so-called slow metabolism and slow metabolism in itself (I mean, how slow is good? Dead is VERY slow. Is that the best?) - is not necessarily a panacea.

Diet is very important. Reducing stress and exposure to toxins like mercury are just as important. With a mouth full of mercury amalgams, you sure might have lowered thyroid output but I doubt you're going to be feeling very well, regardless of how well you are eating. I have the experience to back up that particular statement.

anonymous - November 18, 2010 11:00 PM

I think this has some truth. However, I always sleep better when I eat "excessive" calories. I can only eat 1100-1300 calories daily - my sleep is always bad at this calorie intake. Yet when I eat "excess" calories, I get restorative sleep, but I also gain weight. My metabolism is too slow, and I since I can never eat enough food, I'm doomed to sleeplessness and an early death. I need a higher metabolism, so I can eat more food, and therefore get quality sleep.

Louise - December 18, 2010 11:55 AM

You'll find that metabolism isn't as simple as a speed switch. Having an efficient metabolism is a better way to promote youthfulness. Everytime we exercise our metabolism must become more efficient because our caloric demands increase. Same goes for fasting and calorie restriction. Human growth hormone is released during exercise AND during fasting as a way to maintain the lean tissue in the body. However adrenal fatigue is a real problem on calorie restriction. So, get the benefits of a more effective metabolism from exercise, rather than starving in a state of ketosis which is not good for brain function. Peace.

Jen - May 21, 2012 11:44 AM

wow, the wild and varied interpretation of the information presented in this article is stunning. The varied interpretation of the term metabolism is also stunning.

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