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Is Exercise a Metabolism Booster? Maybe Not.

By , SparkPeople Blogger
Does regular exercise help you burn more fat, even hours after your workout is over? Although a metabolism boost is touted as one of the benefits of physical activity, a new report says that exercisers won't burn more fat after a workout compared to days when they don't exercise.

The report, published in the journal Exercise and Sport Science Reviews, studied people who did a moderate-intensity workout, high-intensity workout or no workout at all (on separate days). They also compared people of different age groups and those who were competitive athletes, versus sedentary obese and sedentary lean individuals. Throughout all of these comparisons, one result was consistent: There seemed to be no difference in how much fat participants burned 24 hours after a workout, compared to days when they didn't exercise.

This study looked at workouts that were under one hour in length, so researchers can't be sure that longer, more intense workouts would produce the same results. The study also discusses the popular belief that weight training dramatically increases metabolism. A pound of muscle does burn more calories at rest than a pound of fat. But most people don't put on enough muscle to make enough of a difference. For instance, if someone gained 4-5 pounds of muscle, that only translates to an additional 28-50 calories burned per day.

So does this mean you should just become a couch potato? Not at all. Exercise can play an important role in weight loss, which ideally comes from a combination of diet and regular activity. Exercise will help you maintain the weight you've lost, and helps reduce the risk of certain diseases like heart disease, diabetes and high blood pressure. It also has mental benefits like reduced stress, more energy and better sleep. Just don't think you can eat a big piece of cake after a workout because you'll burn it right off.

When it comes to weight loss, have you found that diet or exercise is more important? Or is it a combination of the two that have helped you?

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Both diet and exercise are vital in losing weight and getting fit and without the other is a recipe for failure Report
I've tried exercise only and lost a little weight. I've tried diet only and lost a little more weight than just exercise.. BUT and I mean a HUGE BUT.. exercise is way more important to me personally. It makes me feel good both physically and mentally. Obviously it's best to do both.. but I find it easier to eat well when I'm working out regularly because my body demands better fuel. Report
For myself it's a combination of both diet and exercise Report
I think that a combination of both is perfect. Diet needs excercise as well as excercise needs diet. Report
It is a combination of both diet and exercise you cannot have one without the other and be successful you need to be really aware of what you put into your body and what exercise you expend Report
For me it is the combination. I can lose about 5-10 pounds with diet alone, but I plateau VERY quickly. Report
I like this article. Makes us think.
At over 300 pounds, I had over 80 pounds of fat. When I get to 160, I should have about 10 pounds of fat. I know full well that at 206, I have TONS more muscle than I did at 310. So... how much more muscle? Would that TONS be? Hmmm- they don't seem to go in the 'bass ackwards' direction, but I would guess well over 10 pounds of muscle gained in my journey. That is, what, a 100 calories RESTING difference. Add the caloric burn of the exercise itself- (I'm doing between 300-3000 calories burned in a day), and dang, I'm a calorie burning machine compared to the old days.
If your resting burn is 365,000 calories burned more in a year- or a mere smear 187,500 a year... heck, that's still pounds lost, or not gained.
Yeah, muscle!
Yeah, it's all good that we get to keep on doing it. That's the point here- not a one shot, ok, I'm done quick fix, but a lifestyle change... right? Report
I have read the entire original and related studies that this article refers to. There some major flaws in the study itself and misleading inferences in the articles based on it.

The main flaw that remained consistent in all the studies was the use of 'steady state' AEROBIC exercise protocols as the stimulus. Our aerobic energy systems use oxygen combined with glucose to create fuel for our bodies. Mother Nature made this an extremely efficient process for us to conserve our valuable energy stores. So of course fat metabolism and overall energy expenditure in a post 24 hour period will be insignificant based on this type of stimulus – the metabolic demand, in this particular case, is too low! This does not mean there are not cardio-respiratory and other great benefits of aerobic exercise (post workout or otherwise), there definitely is, but that’s another topic.

Now, if they substituted ANAEROBIC activity (resistance training) in this study, specifically a form which targets both the ATP and glycolytic energy systems, I guarantee you would see significant levels of post-workout 24hr fat metabolism. Anaerobic activity uses up the immediate ATP and glycogen (glucose) stores in our muscles for energy at a much higher rate. Up to 19 times more glucose is required with anaerobic exercise to get the same energy production when compared to the aerobic breakdown of glucose. (Note: glycogen is converted from the glucose in our blood stream which in turn is produced by eating and digesting carbohydrates)

It makes sense that in replacing these spent glycogen and ATP stores, we are using up excess ‘energy’ that would otherwise be converted and stored as fat. In addition, our fat stores are ‘dipped into’ and slowly burned up during our rest periods throughout the day/night because our overall metabolism is increased in order to fuel all the process that go along with strengthening, rebuilding, repairing and maintaining lean muscle tissue, ligaments and tendons. Not to mention the HUGE and much understated metabolic demand on our nervous system (including the brain) after intense anaerobic exercise. The brain uses 25% of our total body glucose utilization! Anyone that has worked with weights, bands or done HIIT/MET/Hybrid or plyometric training knows the mental focus and extremely taxing neuro-muscular requirements.

Other problems with the studies:
-The original study used subjects with above average fitness levels and VO2 Max capacity (42.6-45.0 ml/kg/min). They were already working out 3-5 times per week.

-On top of the already high fitness levels the intensity levels for the aerobic activity were considered moderate (avg. 66-67% of VO2 Max), not ‘high intensity’ as the study claimed. In other words, the workouts were not near difficult enough to illicit any significant change or adaptation in overall physiology or metabolism in these particular subjects – fat burning or otherwise. You can’t say, “Oh I went for a stroll in the park and was surprised I didn’t burn any fat the next day.”

-The ‘obese’ subjects in the supporting study were labeled based on the BMI index which is outdated and ambiguous (Most ATHELETES due to their high proportions of lean muscle are considered obese on the BMI chart! It’s not a sound measurement on it’s own). Plus they did not indicate there fitness levels, so we don't know how efficient they cardio-respiratory systems were in the first place.

There was more but, the main point that supersedes all is that the inference based on the the study is misleading from the get go (ie: aerobic activity at these levels would not correlate strongly to post workout fat burning in the first place).

I also take issue with the stat that the average fitness enthusiast gains only 4-5 lbs of muscle. That really sets the bar low for us, especially if you’re a male of average height. Potential for lean muscle gain is easily double or triple this with a proper program - no super genetics required!

The icing on the cake is that the original study was done over 8 years ago and was originally designed NOT to say we don’t burn fat post-exercise, BUT intended to dispel the notion that low intensity exercise was the most efficient for burning fat. Which it does successfully and I give it credit for, but this is old news. (By the way, it also recommends regular high-intensity exercise in the conclusion of the paper)

It’s obviously a case of some weak studies compounded on one another over time and the media has twisted it, taken it out of context and turned it into a sensationalistic headline with only half the facts.

The bottom line in terms of post exercise fat metabolism…YES, the correct exercise will turn up your 24hr post-workout metabolism and in turn burn fat for fuel!!

Of course eating properly and living a healthy lifestyle go without saying.

I hope this makes sense and alleviates some confusion…

Happy training,
BJ Report
In my experience, exercise is extremly important for a variety of health related benefits, with weight loss being just one of them. However, unless one is exercising almost continuously over a sustained period, I don't believe it is possible to lose a significant amount of weight without also eating healthily .

The only way to lose weight is by having a calorie deficit - i.e, to eat less calories than you burn each day - and it is going to be very difficult to achieve this deficit unless one carefully monitors what is being consumed. How easy is it to overeat without even realising it? Nevertheless, every individual reacts differently to different things and therefore needs to be strong willed to keep on track to successfully reach their target weight.

I find that I have to chop and change the way I eat in order to keep getting results week after week. I effectively have to fool my body so that it doesn't get used to a particular style of eating and then adapt to it.

It is a huge battle, but great willpower will triumph in the end, we just have to consistently keep at it and not give in as soon as we meet a hurdle. Report
I think both are important, but for me personally, exercise helps me more, at least at this point. I already eat pretty healthy and can't eat any less than I already do, so I need exercise in order to push my body past that plateau. But I still need both diet and exercise in order to maintain where I am now. Report
They aren't saying exercise doesn't burn calories. They are just saying that it won't boost your metabolism the rest of the day. True or not, I do know that when I exercise, I drink more water and tend to crave healthier foods. For some reason, I also tend to eat a little LESS. (All that water probably.) So, it's a major part of my weight loss plan.

That said, I can maintain my weight though portion control alone. I might even be able to loose some, but not much. When I'm really having trouble with my health (mostly migrianes), I frequently can't exercise. But at least I know that if I stay in my SparkRanges, I won't gain. Report
both but I have to exercise or the weight will not come off and stay off Report
Frankly, I don't care what the studies say at this point. If I had just been starting out this artical would probably be discouraging. But having lost almost 70 pounds with both counting calories/eating healthfully AND exercise, the study is moot. I can testify that I need to do both in order to lose my excess weight. AND I feel so much better from both! Report
I thought I had read another article on here not long ago that said kind of the opposite. This is kind of confusing and not encouraging. I thought you had to I continue as I've been doing or should I exercise less? This article is not one that seems very helpful. JMO Report
Ok . . . let's not freak out here!

Look at the time period that was tested and what was tested/compared. They didn't compare the overweight people's metabolism against the inshape peoples metabolism. They compared the metabolism of each person against THEIR OWN. So they tested it 24 hours after a workout and then tested on a day that there was no workout. They are comparing patient A (day one) to patient A (day two) rather than patient A vs. patient B. Also, it sounds like they did these pretty close together. So of course you're not going to see much of a difference. But if they would have tested them a few MONTHS apart . . . patient A (month one) vs. patient A (month four) . . I bet you'd see a difference in those numbers.

And I would have loved to have seen the comparison between patient A (overweight) vs patient B (in shape). I can almost guarantee you that the numbers would be totally different.

It's always good study to read exactly what they're comparing . . . shines a bit of light on the "Breaking News Working Out Doesn't Affect Your Metabolism!!" hype.

Of course it does!!!

any one of you who've been working out regularly and eating healthy KNOWS how much better you feel!!!! Report
I need to exercise and watch my food intake, doing one without the other dose not work for me. Report
I have found that I can lose weight with just diet alone, BUT I feel better and am healthier overall when I exercise as well. Report
in my 20's I would have said...exercise, exercise, exercise is ALL I that I'm 37...DIET AND have to have both!!! Report
Definitely a combo of diet and exercise has helped me lose weight. I think the exercise not only helps me get fit, but also keeps me feeling happy, which translates to eating less! Eating healthier makes me feel good, and that makes me want to get out there and DO things (like exercise). So it is a win-win situation - BOTH diet and exercise are my keys to a healthier life. Report
I wouldn't be where I am without both exercising and eating right! I have noticed that this past week, when I haven't exercised much, I've gained back a couple of pounds. Report
I think exercise has helped me LOOK like I've lost more weight than I really have. I don't know if it is because I am building muscle, which takes up less space, or whatever, but my weight hasn't changed and I've gone down a clothes size. So, I won't give up my exercise routine - cardio, weights, stretching, stability, and balance work. I do something different every day. Report
It's a combo of both, calories vs calories out. Eating healthily and exercise is not just for WT loss it also makes you fit and stronger. Report
These articles are disturbing, as one year they say one thing and the next year its something else. I have heard many say that they lost weight just by cutting things out of their normal diet, or cutting down, or just taking a walk down to the end of the driveway. In other words anything you do differently should cause you to loose a pound or two. I love this site though and yes I do have to exercise as I have gone without eating at all for 5 days and didnt loose a thing. Now that I have cut back on things (switching to diet products such as splenda, lowfat milk, smaller portions, no fat etc.) and am exercising at least 40 minutes a week, I seem to be getting some where. I do however need hoodia to cut my appetite and a dieters tea to keep the insides clean. Is anyone using any type of diet product to burn fat or colon cleanse or appetite suppressent? Report
I don't know that I ever heard that a single workout lasts more than a few hours after the workout for revving the metabolism and helping to lose weight, so I didn't think this was much of a revelation--that it's not still working 24 hours later. The main reason I exercise is to keep my bones, lungs, and heart strong, not just to help in losing weight. I'm not disappointed in this information, just a bit confused. Report
This is sorta discouraging. Report
I lost 82lbs in about 7 months, so I'm going to continue to do what I'm doing since it works for me. :-) Report
I agree with most here. You need both. Studies as always are confusing and change with the wind. I stick with what works for me and that is eating right and staying active. Report
For me, exercise changes my body shape in ways that diet doesn't. Plus, it gives me energy and improves my mood. So I'll take the slight metabolism boost it gives...that's better than none at all! Report
I agree with some of the other posters in that this doesn't change anything for me. I lose weight when I eat right and exercise, and not when I do just one of those things. Of course I didn't expect to be burning more calories a full day after exercising. That would be absurd! Of course a good workout doesn't entitle me to a big bacon cheeseburger and fries. That would also be absurd! We all know that there's no outrunning a bad diet, and this just supports that. Report
I can loose some weight while watching my cal. intake. I find that I look better in my new smaller clothes if I take the time to exercise.The reults of a more toned and better looking body comes from exercise. For me it takes both diet and exercise. My thought is I can look good in my new size but I can look REALLY GREAT in my new clothes with a curved and toned body. Report
i think you can't loose weight unless you do both Report
No matter how restrictve my diet, I can not lose weight without serious exercise. And even with logging hours of cardio under my belt, the belt will be remain snug (or tight during certain days :) without consisent strength training. Some months I have to travel 11-15 days and it is during these months that I've noticed my inability to not only lose, but maintain my weight without the serious strength training. Thank goodness for the hotels that have free ExerciseTV! The corporate firewalls on my company lap top often make it impossible to access the internet or run the SparkPeople videos, so I was thrilled to discover ExerciseTV videos on FREEVIEWS on certain hotel chain TV's. I now make a concerted effort to stay at these chains when traveling otherwise I come home feeling flabby and unfit. I especially love the 12 minute standing/crunchless abs routine. Report
I love exercise and often exercise more than an hour a day and have been doing so (in phases) for more than 10 years. I have found that exercise ALONE will not help me loose weight. For me to loose weight diet is 80% of the equation and exercise is the other 20. Exercise seems more important for maintaining weight loss. And exercise is a mental thing - I feel better about my body and myself when I am working out. Report
In terms of strictly losing weight, I have always found that exercise matters a lot more for me. My weight will fluctuate based on my activity level, even when my diet does not change at all. Even if I'm less active and have cut back my calories to try and compensate, I am STILL prone to gain if I don't get at least a 2 hours a week or so of walking or other cardio.

On the other hand, my diet seems to make more difference in how my waist and stomach look, regardless of how much cardio and crunches I'm doing! Too much sodium and sugary carbs, too little fiber = belly bloat, even if I'm working out for an hour and a half a day.

All that being said, weight loss is easier and generally more consistent when I am watching my food intake too. Report
I believe you need both to suceed. I didn't start to lose until I combined both diet and exercise. Report
ALSO...being active allows us to have those days where we splurge on treats....I would imagine the excersise keeps us functioning at a higher level so that those extra calories in the burger and fries won't do as much damage. And with all our organs functioning better the dangerous side to those calories are less damaging.

This is all supposition on my part.

It does make sense though....most of our body is muscle and muscle needs to be worked to keep it in shape - even our brain to some degree is like a muscle.

Good article that is giving me an ' ah ha' moment......revelations come in all Report
I have found if I do more I lose more; yes, I lost weight by just eating fewer calories but when I added exercise I lost more. It may not continue for the next 24 our, but I think that when your body consistently burns a higher average per day it will continue to burn that higher average. One days activity isn't going to make it work, but over time you will train your body to burn more so it will. Just like training your body to go to sleep and wake up at a certain doesn't just happen over night, you have to force your body to do it then eventually it will do it on its own. Report
i think you can't loose weight unless you do both.
You need both. I finally combined good eating and walking. I have lost 17.4 lbs & 14 inches in 10 weeks. Try it! Report
After a lifetime of doing one or the other and not finding consistent success, then finally getting both eating right and exercise together - I'm convinced I need both. Everybody's body is different, but I am one of the people that must do both. Report
I think its a combination of the two that helps you lose weight. It also helps you gain muscle. They say you can't lose weight if you are under your calories but I bet you could gain muscle. I have seen myself do that. Report
Definitely a combination of the two. And as far as eating a big piece of cake after my workout, I always remember that usually my exercise is not extra calories burned that allows me to eat what I want. I have my calorie burn calculated and SparkPeople has matched my calorie intake needed to meet my goals. If I would choose to eat that big piece of cake, which would be a poor empty calorie choice, it still needs to be counted into my calories for the day, or the exercise will have done me no good at all.

Also, I have a co-worker who started jogging about the same time I started walking and changing my eating habits. She chose not to change her eating habits. We both walk/jog 3X per week, and she has not lost any weight while I have lost 25. Granted, with my weight, I know that I will lose much faster than someone who only has 20 pounds to lose, but I think this is a testament, that exercise alone is not the key. Report
Exercise has always been far more productive for me. I'm not very good at dieting because I rarely eat much anyway so I don't have much leeway and I guess I'm pretty stubborn about what I want and what I don't want. Spark People has me eating substantially more, but so far the balance to include food that keeps me stuffed hasn't helped to make me loose weight. I haven't gained much either though, but a little. Other times people tried to get me to eat differentlly (aka more) I gained substantially. Report
absolutely a combination of both! without changing my diet (to vegan), i would've never had the energy, focus, motivation, etc., to exercise and LOVE IT, as much as i do. my body and mind feel continually optimized and my body is finding its own natural weight (which will probably be less than my weight loss goal). Report
For me it has definitely been a combination of the two.

I saw a trainer and a nutritionist every week last month. It has helped me tremendously! The nutritionist said that I don't want to be a smaller version of myself. I said "I don't?" He explained that if you just do cardio sure you will lose weight, but you will still have flabby areas - so basically smaller but not as toned as you could be. With weight training, you will be able to tighten up problem areas and help reshape your body - and you cannot weight train without proper nutrition.

He had me eating 6 times a day, lots of green vegetables and protein with EVERY meal. I was able to reduce my body fat percentage by 5% in 2 weeks! Conversely, my friend whom I was splitting the cost of the nutritionist and trainer with decided not to follow the nutrition plan but worked out the same as I did. Because she was eating a lot of junk, her body fat percentage went up. Sure she lost 2 pounds - 2 pounds of muscle!

I believe proper nutrition and exercise go hand in hand if you are looking to rev up that metabolism. Report
I've lost weight both ways -- with diet alone and with exercise alone ... BUT, BUT, BUTTT!!! The scale (Tanita Ironman Innerscan) also shows a decrease in muscle mass with diet alone (bummer); and while being sufficiently active will also take off the pounds, if you're not eating healthy, nutritious foods as opposed to junk and fat, that can't be doing your heart or other organs as much good either.
So, I'm a believer in aiming for good all round habits, and accepting the reality that chances are slim I'll ever be 100% perfect. Report
I see that some people are really disturbed by this article. Bottomline for me is this: I am losing weight following the sparkmenu and doing both cardio and strengthening exercises. That's what I want and that's what is happening. That's all I need to know! Report
I do find exercise to be a metabolism booster, in my case. Since I've been exercising, I've been eating nonstop AND I'm still losing the weight. The key though is the kinds of foods I've been eating. I'm so over fast food and all that saturated fat. Fried foods and some desserts are not on my docket either. However, I eat tons of whole grains, fruits, vegetables, meat and chicken. As long as I exercise though, I find I can eat even the foods I no longer crave. Report
Diet is so much more important. I can pass up a 400 calorie candy bar and find that it takes a hour of running on the treadmill to have burned it off. Report
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