A recent paper provides the groundwork to establish a way for exercise to diminish appetite. Or, more likely, for sedentary behavior to increase appetite.
It is well known that exercise burns calories. Personally, I think that's overrated: Strength building raises your metabolic demand, and THAT burns calories. But that is not the main topic at hand. New research indicates that exercise also increases the sensitivity of neurons that are related to the control of the feeling of satiation. Therefore, you feel full rather than hungry sooner and/or more often.
In rodents. So far.
The research team made obese rodents exercise was found to increase the amount of IL-6 and IL-10 protein levels in the hypothalamus, which in turn changed the threshold for the feedback system that ultimately releases insulin and leptin, which are the magic juices that seem to affect hunger and related system. Indeed, leptin has been seen for some time as a key to understanding weight control, has been implicated in various concepts like the "set point" and is linked to numerous rather complex systems. What may be happening here is that insulin and leptin levels act one way in the sedentary person and a slightly different way in the active person.
I'm going the gym.
Oh, wait, OK, I'll finish this blog post first.
Here's what the authors say about the study:
The hypothalamus is a brain region that gathers information on the body's nutritional status and governs the release of multiple metabolic signaling molecules such as insulin and leptin to maintain homeostasis. Overeating and obesity are associated with insulin and leptin resistance in the hypothalamus, and recent studies provide an intriguing link between inflammation and dysfunction of hypothalamic insulin and leptin signaling through activation of IKKÎ², a key player in immune response, and endoplasmic reticulum (ER) stress. This means that strategies to reduce the aberrant activation of inflammatory signaling in the hypothalamus are of great interest to improve the central insulin and leptin action and prevent or treat related metabolic diseases. Using a combination of pharmacological, genetic, and physiological approaches, our study indicates that physical activity reorganizes the set point of nutritional balance through anti-inflammatory signaling mediated by interleukin (IL)-6 and IL-10 in the hypothalamus of rodents. Hence, IL-6 and IL-10 are important physiological contributors to the central insulin and leptin action mediated by exercise, linking it to hypothalamic ER stress and inflammation.
And, if you want to know a LOT more about this process, click here to download a PDF primer on Exercise and Hypothalamic ER Stress.
You can read the paper, published in PLoS Biology, here.
Ropelle, E., Flores, M., Cintra, D., Rocha, G., Pauli, J., Morari, J., de Souza, C., Moraes, J., Prada, P., Guadagnini, D., Marin, R., Oliveira, A., Augusto, T., Carvalho, H., Velloso, L., Saad, M., & Carvalheira, J. (2010). IL-6 and IL-10 Anti-Inflammatory Activity Links Exercise to Hypothalamic Insulin and Leptin Sensitivity through IKKÎ² and ER Stress Inhibition PLoS Biology, 8 (8) DOI: 10.1371/journal.pbio.1000465
Nice review. I agree for the most part with this:
"It is well known that exercise burns calories. Personally, I think that's overrated: Strength building raises your metabolic demand, and THAT burns calories."
Most people are considered regular exercisers if they follow the old-school recommendation of 20 minutes a day, three times a week. Go to the Runner's World forums and you'll find that the average participant puts in maybe 15 to 20 miles a week, meaning that he burns about 200 to 300 more calories than he would if sedentary. That's really not much--people like the simpistic approach of saying "That's a loss of one pound every two to two and a half weeks," but in practice a lot of people who have begun exercising consciously allow themselves to eat more, offsetting the potential shedding of poundage.
At my peak I was burning a pound's worth of calories every couple of days (in one calendar year, I averaged 103 miles a week of running), so my situation was different. However, I was never in it for the weight loss. The reality is that for most people diet makes a far greater contribution to weight than does exercise (and I'll omit genetics from the discussion as some like to think it makes no difference).
kemibe, I'm skeptical of your analysis. Maybe the exercise of running alone only burns 200-300 more calories than being sedentary, but what about the additional calories burned from gain in muscle mass? Since I started running 8 months ago (~20 miles a week), my quadriceps have become noticeably larger, which I would guess has resulted in the loss of many more calories while sedentary today, than I would have lost 8 months ago.
I had to cut 3 new notches in my belt over the course of 6 months, and I still eat to satiation.
I am not sure that you two are disagreeing here. On one hand, added activity does not burn off fat at any kind of impressive rate unless you keep your caloric intake low enough that you are dipping into fat reserves often, and/or biking the Tour de France.
On the other hand, whatever activity you do, including sitting there watching TV, will burn energy at a rate proportionate to your muscle mass, so adding muscle mass will give results perhaps better than a longer run, depending.
This leads us to this: If you are going to spend X minutes a day working out, should it be pumping iron to get those quads (and glutes... they're bigger, so they burn even more) larger or do you spend it highly active ("aerobic") to burn off calories?
Answer: Some well designed plan that involves both. Get the muscle mass up fast and use it heavily.
I'd like to know this: What about swimming? The physical exercise is good, but it seems to me that being in a 70 degree pool will burn off a lot of calories just staying warm.
""It is well known that exercise burns calories. Personally, I think that's overrated: Strength building raises your metabolic demand"
But mostly because exercizing muscles use energy; if exercize didn't burn calories there would be no need to increase metabolic rate with strenght building.
So that's not overrated at all!
Best stick to archeology & anthropology..
Nah, Greg's right. Any well-designed weight loss plan will use strength and endurance training both; but of the two modes of exercise the more important component is diet - all the exercise in the world won't make a single bit of difference without actually controlling energy intake. It's fully possible to run a couple 10K's a week and not lose a single gram due to overindulgence in Gatorade or corn chips.
'course, when comparing the effect of diet and exercise it's also important to note that endurance exercise is generally a trivial component of any effective weight loss plan; the important bit is getting your strength training in. Adding endurance exercise to a strength-training plan will enhance results, omitting strength training will worsen them. The key component then, is diet and strength training with endurance exercise done on an "as time allows" basis.
A better diet without exercise is useless.
...but what about the additional calories burned from gain in muscle mass? Since I started running 8 months ago (~20 miles a week), my quadriceps have become noticeably larger, which I would guess has resulted in the loss of many more calories while sedentary today, than I would have lost 8 months ago.
This is probably an optical illusion. Running will add muscle only for the severely sarcopenic. Muscle is gained only from high-load low rep exercises to near exhaustion, and running is a low-load high-rep exercise. Increase in muscle mass comes from building more myofibrils [actin, myosin, troponin, tropomyosin mostly] Endurance exercise builds mitochondria which take up only asmall amount of the muscles' mass.
What you are seeing is your muscles showing more definition because you have lost subcutaneous fat. The fact that you had to cut new holes in your belt confirms this - you have lost much of your pinchable fat under the skin and the fat around your internal organs [the bad stuff].
Energetically, running, biking etc burns far more calories per minute during the exercise than strength training. Strength training builds more muscle to expend more energy at rest.
What about swimming? The physical exercise is good, but it seems to me that being in a 70 degree pool will burn off a lot of calories just staying warm.
First of all, very few pools are kept anywhere near 70 degrees. You can find lots of lakes at that temperature, but that's just too cold for most water activities for any length of time. Most pools are kept in around 78-84 degrees. Competitive training can be done in slightly cooler water. 84 feels slightly cool, 78 feels cold when you first get in.
And swimming is a good exercise for cardiovascular conditioning, but there have been some suggestions that exercise in water may not have the same salutary effects as an equivalent amount of dry land exercise. It may have to do with the coolness of the water keeping the core temperature down which somehow changes the release of appetite controlling hypothalamic hormones. There has been little or no experimental results to back this up, but it hasn't been rigorously studied AFAIK.
...added activity does not burn off fat at any kind of impressive rate unless you keep your caloric intake low enough that you are dipping into fat reserves often ...
All exercise will cause you to dip into your fat reserves, although high intensity-short duration will utilize fat only during recovery. The longer you exercise, the greater the proportion of fat will be used to support the activity as your muscle glycogen stores wane. [i.e. 35% @ 15 min; 60% @ 60 min; 80% @120 min at the same speed]
I find cycling is the best all rounder .especially for toning the bottom and legs . also when i had a back injury sometime ago my physiotherapist encouraged me to begin cycling once the acute phase was over .I was back to normal soon after
It may have to do with the coolness of the water keeping the core temperature down which somehow changes the release of appetite controlling hypothalamic hormones. There has been little or no experimental results to back this up, but it hasn't been rigorously studied AFAIK.
I'm sure this has already been worked into the Aquatic Ape Theory, but just in case, I may send Elaine a memo...
Hey great post Greg! I especially liked the quote "I think that's (exercise) overrated: Strength building raises your metabolic demand, and THAT burns calories." ... Well written post with some great info put forth in a straightforward manner. Now I know why long sessions on the treadmill were not giving any results! LOL..
Awsome post i'd like to read more about this but the link in:
You can read the paper, published in PLoS Biology, here. redirects me to a "404 not found" any chance you would check that out?
"The best exercise is the one you'll do."
- Covert Bailey
It doesn't matter what form exercise comes in, even if it's the single most efficient way to burn off fat and get fit. If you hate doing it, you won't do it. The key is to find something you like, something fun.
As for eating more when unhealthy less when exercising, it could also be a product of emotion, not just chemical. Depression has a known link to overeating, and when someone is unhealthy, it causes the person to eat more. When someone becomes fit, the person eats healthier and eats less.
It's only anecdotal, but I can testify to that effect in the past year when I decided to make a serious effort at improving my fitness level and losing weight. A year ago and eight kilograms heavier, I ate a lot - not so much junk food, but constant eating. Now that I'm fit, I snack mostly on oranges and apples and drink water instead of packaged "beverages".
I find that when I exercise, I don't get so hungry and I tend to want the healthier foods.
I think moderation in everything is key and we should just change to healthy diets and take some form of exercise a few times a week.