Being Sick Raises Metabolic Rate?

NCchar130

Someone told me once that being sick raises your metabolic rate. I googled this every way I could think of, and couldn't find any information I thought would be reliable. I was just curious about this and whether it applies to any sickness, even, say, a head cold. If anyone has some information or some links to good sources, I'd love to hear it.

NCchar130

bump!

SideSteel

I've never seen anything that conclusively measures this (doesn't mean it's false -- just saying I've never seen it).

Additionally, lets just suppose your resting metabolic rate increases while your body fights off an illness. Your activity, in most cases (especially during illnesses beyond the common cold) would plummet. Activity driven thermogenesis would significantly drop.

Graelwyn75

Not sure, but even eating a load when he had the flu, my bf lost weight and is already thin.

TopazCutie

I typically lose weight when I'm sick. I don't think it's because my metabolism is raised though -- more because my appetite is gone.

NCchar130

I've never seen anything that conclusively measures this (doesn't mean it's false -- just saying I've never seen it).

Additionally, lets just suppose your resting metabolic rate increases while your body fights off an illness. Your activity, in most cases (especially during illnesses beyond the common cold) would plummet. Activity driven thermogenesis would significantly drop.

Yeah, that's a good point. I've caught some horrible bug and am not working out right now due to the body aches/chills. I'm tracking my food but not worrying about restricting calories. My appetite is fine and no GI issues so I've been eating around TDEE or slightly above. Hoping I can get away with it. But either way, I think I just won't worry about it and do whatever I need to do once I get myself well.

SideSteel

I've never seen anything that conclusively measures this (doesn't mean it's false -- just saying I've never seen it).

Additionally, lets just suppose your resting metabolic rate increases while your body fights off an illness. Your activity, in most cases (especially during illnesses beyond the common cold) would plummet. Activity driven thermogenesis would significantly drop.

Yeah, that's a good point. I've caught some horrible bug and am not working out right now due to the body aches/chills. I'm tracking my food but not worrying about restricting calories. My appetite is fine and no GI issues so I've been eating around TDEE or slightly above. Hoping I can get away with it. But either way, I think I just won't worry about it and do whatever I need to do once I get myself well.

Bold part is a great idea in my non expert opinion.

neurochamp

When you are running a fever, your body is cranking up its metabolism to raise your body temperature above its normal "set point"; increasing your metabolism does two things in this case: (1) an elevated body temperature (fever) can help inhibit the growth of certain pathogens (bacteria or viruses) that cause illness and damage to your body, and (2) an increased metabolism can help your body's own cells produce the chemicals that it needs to fight an infection.

A short answer to your question is that yes, being ill does increase your metabolism, but I would imagine that this increase is only significant when you're running a fever (hence previous poster's comment that the bf lost weight while sick with the flu, even though he ate a lot of food - extra food is needed to maintain the fever, which in turn helps to fight the flu virus).

Unfortunately, I can't give you easy-to-find online sources, as I'm working from the textbooks I use to teach college biology classes (e.g. Campbell's Biology; Sherwood's Fundamentals of Physiology; Goodenough & McGuire's Biology of Humans).


Edit to add: I wholeheartedly agree that it's OK to log your food while running a fever, but don't worry about going over on calories (if you are hungry, eat) - you need the extra nutrition to support your immune system, and MFP cannot accurately account for that. Do what you need to do (eat, rest, take a break from exercise) to get well, then resume your usual tracking and activities.

SideSteel

When you are running a fever, your body is cranking up its metabolism to raise your body temperature above its normal "set point"; increasing your metabolism does two things in this case: (1) an elevated body temperature (fever) can help inhibit the growth of certain pathogens (bacteria or viruses) that cause illness and damage to your body, and (2) an increased metabolism can help your body's own cells produce the chemicals that it needs to fight an infection.

A short answer to your question is that yes, being ill does increase your metabolism, but I would imagine that this increase is only significant when you're running a fever (hence previous poster's comment that the bf lost weight while sick with the flu, even though he ate a lot of food - extra food is needed to maintain the fever, which in turn helps to fight the flu virus).

Unfortunately, I can't give you easy-to-find online sources, as I'm working from the textbooks I use to teach college biology classes (e.g. Campbell's Biology; Sherwood's Fundamentals of Physiology; Goodenough & McGuire's Biology of Humans).


Edit to add: I wholeheartedly agree that it's OK to log your food while running a fever, but don't worry about going over on calories (if you are hungry, eat) - you need the extra nutrition to support your immune system, and MFP cannot accurately account for that. Do what you need to do (eat, rest, take a break from exercise) to get well, then resume your usual tracking and activities.

Can you make an attempt to quantify the above or do you know of any research to support this? I'm not calling into question the validity of the claim, but I'd be interested to see how much of an increase this.

neurochamp

Sorry, I don't know offhand *how much* a fever of X degrees would increase a person's metabolism, only that, in general, it *does* increase metabolism. Shivering and constriction of the blood vessels are major mechanisms to increase body temperature when you're running a fever; both of these require the use of ATP; in order to build ATP, your cells (especially in your skeletal muscles and liver - major glycogen stores) must break down glycogen into glucose to fuel aerobic cellular respiration.

This is the same process used when you exercise (you need ATP to contract your muscles to lift weights or run, and you need ATP to contract your muscles to shiver...it's the same fuel source, just different body conditions), but I would imagine that the *amount* of sugars you "burn" to build ATP and maintain a fever depends on your initial glycogen stores, your food consumption (blood sugar levels), your activity level, your dress (whether or not you're wrapped up in blankets to help raise body temp, etc.) and whether or not you've taken any NSAIDs to reduce your fever (thus reducing your need to shiver and burn calories). There are a lot of factors to consider.

In all honesty, I would be interested to know a quantitative measure of this as well (I lost more than 5lbs earlier this year fighting a terrible cold that lasted 2+ weeks, with fever on-and-off... I couldn't exercise if I tried and I ate whatever I could stomach; I'd be interested to know how off-kilter my metabolism was at the time), but a cursory glance through my school's library database isn't turning up any research papers that look even remotely helpful/informative on the subject (but I'll definitely post if I come across any!). Hopefully somebody else has something more useful to add, sorry!


BTW, I'm honestly not just spouting BS I've learned on the internets - metabolism is not my specialty, but I do have a PhD (in neuroscience; from a Big10 school) and teach biology and psychology at the college level. I would give specific references for the info I'm stating about ATP/muscle contraction/aerobic respiration (and hypothalamic regulation of body temperature, inflammation & fever, and other general body responses to injury and illness), but I'm pulling from like 6-7 different textbooks that I use/have used in the past (some mentioned in my previous post), and multiple chapters from each. If it would be helpful to you (or others) to cite these books or elaborate on anything I said above, I will gladly do so (as long as I have spare time between class preps for the spring semester) :drinker: