Claim#2: Adding Muscle Boosts Your Metabolism

This is entry #2 in a 9-part series on Metabolic Myths.

Metabolism-boosting hype generally has a grain of truth behind it that has been way overblown. In other cases, long disproved theories continue to be touted because they are super effective as click-bait (or selling books). You rarely see any actual numbers -- how many calories per day will this raise my resting metabolic rate? -- attached to claims. That’s because for the most part the actual increase in resting metabolic rate (or other components of your daily total energy expenditure), is too small to be of any practical significance.

Metabolism mythology has a life of its own though as it gets regurgitated and reposted throughout the internet and fad-diet books (and unfortunately even by many otherwise reputable sources).

Review "Metabolism" here: Metabolic Rate

My last topic was breakfast, today's topic is muscle:

CLAIM: Adding muscle boosts your metabolism or aids in weight loss

Muscle burns more than fat (at rest) so adding muscle will (technically) increase your resting metabolic rate.

It's not that simple, however. Following are two points that essentially throw cold water on this oversimplification.

1) You can't actually ADD muscle while losing weight. The best you can do -- if weight loss is your goal -- is to minimize the loss of skeletal muscle over the weight loss process. The back-story is that when you gain weight you gain both lean body mass (LBM; i.e. muscle) and fat mass (FM)... and then in reverse, when you lose weight, you tend to lose about the same ratio that you gained. The two major factors that impact your change in LBM are actually a) the magnitude of energy deficit you're in, and b) the protein content of your diet.[1][2][3] You need a minimum of 1.2-grams of protein per/kg (2.6-grams/pound) of your body weight to minimize loss of LBM.[4][5][6]

2) Improving your body composition has an insignificant effect on your resting metabolic rate.

If weight loss isn't your goal and you just want to improve your body composition, what could you expect as a good outcome from a strength training program?

Let’s say you engaged in a regular strength training program (spending 120- to 180-minuets per week) for a few months and gained 5 pounds of muscle while also losing 5 pounds of fat. This would be a huge achievement, and a result that a small minority of exercisers are consistent enough to achieve.[7] At the end of the day, the net increase in your resting metabolic rate would be just 19.5 calories per day.

Why so little? Both skeletal muscle and fat (adipose tissue) have low resting metabolic rates (5.9 and 2-calories per pound respectively).[8] The type of muscle (lean body mass) that does burn a lot of calories at rest is organ tissue (heart, brain, kidneys, etc.).[8][9] Strength training won’t increase organ mass.

Here's the math:

[(5-lbs. muscle x 5.9 = 29.5) - (5-lbs. fat x 2 = 10) = 19.5]

That is an increase, but it has no practical significance.

Thankfully, there is some good news.

You will have lost inches from your waist and/or hips, and you will feel better. In fact strength training has been shown to lower (systolic and diastolic) blood pressure, improve insulin resistance, lower LDL-(bad)cholesterol and triglycerides, and raise HDL-(good)cholesterol.[4] Your self-esteem might even be higher.

Strength training clearly has many benefits, but for the average Joe or Jane (who wants to lose weight), increasing your resting metabolic rate isn’t one of them.

While the best advice is that you try to limit your loss of muscle while you lose weight, it's important to understand that your "metabolic rate" will always be smaller when you are smaller!

Sorry, but it is what it is!

All the best!
-Dorene

References:

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[1] Weight Loss Composition is One-Fourth Fat-Free Mass: A Critical Review and Critique of This Widely Cited Rule. Heymsfield, et al. Obes Rev 2014;15(4):310-321.

[2] Lean Body Mass-Body Fat Interrelationships in humans. Forbes, GB. Nutr Rev 1987;45(8):225-231.

[3] Body Fat and Fat-Free-Mass Interrelationships: Forbes' Theory Revisited. Hall, KD. Br J Nutr. 2007;97(6):1059-1063.

[4] American College of Sports Medicine Position Stand. Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults. Donnelly, et al. Med Sci Sport Exercise 2009;41(2):459-471.

[5] The role of protein in weight loss and maintenance. Leidy, et al. Am J clin Nutr 2015;101(suppl):1320s-1329s.

[6] Exploration of protein requirement during weight loss in obese older adults. Weijs and Wolfe. Clin Nutr 2016;35(2):394-398.

[7] Body composition in sport and exercise: directions for future research. Wilmore, JH. Med Sci Sport Exerc 1983;15(1):21-31.

[8] Specific metabolic rates of major organs and tissues across adulthood: evaluation by mechanistic model of resting energy expenditure. Wang, et al. Am J Clin Nutr 2019;92:1369-77.

[9] Elia M: Organ and Tissue Contribution to Metabolic Rate, In: Kinney J, Tucker HN (eds). Energy Metabolism: Tissue Determinants and Cellular Corollaries. New York, NY: Raven Press, Ltd.; 1992:61-79.

CLAIM #1: Breakfast Boosts Your Metabolism... (#1 of 9 "Boost Your Metabolism" Claims that are Actually False)

Metabolism-boosting hype generally has a grain of truth behind it that has been way overblown. In other cases, long disproved theories continue to be touted because they are super effective as click-bait (or selling books). You rarely see any actual numbers -- how many calories per day will this raise my resting metabolic rate? -- attached to claims. That’s because for the most part the actual increase in resting metabolic rate (or other components of your daily total energy expenditure), is too small to be of any practical significance.

Metabolism mythology has a life of its own though as it gets regurgitated and reposted throughout the internet and fad-diet books (and unfortunately even by many otherwise reputable sources).

Each of the following false and misleading "Boost Your Metabolism" topics will be discussed in a separate blog over the next couple weeks (not necessarily in this order): Breakfast, Build Muscle, Meal Frequency, Water, Cheat Meals, EPOC, Hot Peppers, MCTs, and Eating after 7pm.

Myth #1: Breakfast boosts your metabolism.

Claims and advice that eating breakfast in some way promotes weight management continue to be doled out despite a lack of evidential support.[i] This problem is so pervasive that it was the topic of a 2013 scientific paper (by highly respected researchers from University of Alabama at Birmingham's NIH-funded Nutrition Obesity Research Center) basically admonishing the scientific community for biased research, and calling on it to do better.[ii]

Some of the false claims regarding breakfast:

CLAIM: Your metabolism will be higher all day if you start with breakfast

The FACTs: the metabolic response to eating breakfast is not different than that to eating food at any time later in the day.[iii] Digesting and assimilating what you eat is called the thermic effect of food (TEF), and by definition TEF is measured as the energy expenditure above resting metabolic rate in response to eating.[iv] [v]

CLAIM: Skipping breakfast leads to overeating later in the day.

The FACTs:  When breakfast is omitted from the daily meal pattern (skipped) calorie intake at the end of the day is generally lower. In other words, the calories missed at breakfast are not completely offset by eating more at lunch or dinner. So at the end of the day an energy deficit remains.

CLAIM: Skipping breakfast makes you hungry.

The FACTs: The effect of breakfast on satiety is transient and not more advantageous than the next meal of the day provides independent of breakfast.[iv]  Note however, that habitual breakfast-eaters and habitual breakfast-skippers respond differently. That's because your body adjusts to the pattern you usually follow so that it "expects," that pattern. So if you usually eat breakfast, and you try skipping it you’re going to be extra hungry for lunch. On the other hand, breakfast skippers aren’t hungry for breakfast to begin with, and eating breakfast is like a curve ball disrupting their system in a different way (which may be why some people claim that eating breakfast makes them more hungry).

Evidence (from well done randomized controlled trials) does seem to show:

• That breakfast eaters may have higher morning physical activity levels (via less sitting/more moving around) compared to breakfast skippers.[vi]
• People who regularly eat breakfast tend not to be night eaters, so they are hungry when they get up.
• Habitual breakfast eaters also tend to be non-smokers, consume less fat and alcohol but more fiber and micronutrients, and are more physically active.[vii]

Clearly, trying to attribute differences in BMI between breakfast eaters, or skippers, is not a straightforward endeavor.

It is important to note that for diabetics eating breakfast results in lower insulin and blood glucose levels for the rest of the day. So, it is very important that diabetics eat breakfast.

For everybody else, you can stick with what works for you because eating breakfast does NOT increase your (resting) metabolism, improve appetite regulation, or reduce overall energy intake. TEF from breakfast is no different, and provides no advantage over, the TEF from any other meal.

The problem with boost-your-metabolism myths is that they distract you from focusing on what actually works, and propagate the notion that there are simple tricks or magical methods that promote weight loss. The best advice remains to be: eat a healthy diet, but not too much, and make activity a part of your day.

All the best!
-Dorene

References:

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[i] Meal skipping and variables related to energy balance in adults: a brief review, with emphasis on the breakfast meal. McCrory, MA. Physiol Behav 2014;134:51-54.

[ii] Belief beyond the evidence: using the proposed effect of breakfast on obesity to show 2 practices that distort scientific evidence. Brown, et al. Am J Clin Nutr 2013;98:1298-1308.

[iii] The Energy Content and Composition of Meals Consumed after an Overnight Fast and Their Effects on Diet Induced Thermogenesis: A Systematic Review, Meta-Analyses and Meta-Regressions. Quatela, et al. Nutrients 2016;8(11)670.

[iv] The effect of breakfast on appetite regulation, energy balance and exercise performance. Clayton and Lewis. Proc Nutr Soc 2016;75(3):319-327.

[v] Effect of breakfast skipping on diurnal variation of energy metabolism and blood glucose. Kobayashi, et al. Obes Res Clin Prac 2014;8(3):e201-98.

[vii] The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial. Dhurandhar et al. Am J Clin Nutr 2014;100:507–13.

[viii] The causal role of breakfast in energy balance and health: a randomized controlled trial in lean adults. Betts, et al. Am J Clin Nutr 2014;100:539-547.

Alternate Day & Intermittent Fasting—Magic for Weight Loss or Just Another Fad?

There has been an explosion of diet books (The Fast Diet, The 5:2 Diet, The 8-Hour Diet, etc.) suggesting that manipulating the time frames you (allow yourself to) eat within can create metabolic-magic leading to easier and/or greater success with weight loss.

There are multiple possible time frame variances among these protocols, including:
a) limiting eating to the same 8-hours daily,
b) an alternating pattern of under- and over-eating days,
c) having two fasting days per week and eating normally the other 5 days,
d) having regular splurge days (in the middle of stretches of calorie restriction), and on and on.

Some authors even suggest you can splurge and eat as much as you want of whatever you want, on the non-fasting days and still lose weight. That’s the kind of promise that causes diet books to fly off shelves!

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The Game of Weight Loss has Rules

What are your odds of winning a challenging game that you don’t know the rules to? Not so great. Likewise, if you're trying to lose weight but don't understand how your body works, your odds of success aren't good.

You need accurate information about how your body works:

• How many calories do I need to eat?
• How many calories should I burn in activity each week?
• What changes can I expect during weight loss (in my energy needs)?
• How do I stabilize at my goal weight?

Click to read more ...

Eating More Often Does NOT Boost Your Metabolism!

How many times have you heard the advice to eat more often (i.e. three meals, and two or three snacks per day) because you will supposedly burn more of the calories you eat because eating more often boosts your metabolism?

If you think the claim sounds a little fishy, your instincts are good—the claim that eating more often boosts your metabolism is completely false.

Here’s all you need to know. A small part of your total energy expenditure is called the thermic effect of food (TEF). TEF simply represents the amount of energy (calories) your body uses to digest your meal. On average TEF amounts to just 10% of the calories in your meal.

Click to read more ...