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Why Doesn't Exercise Lead To Weight Loss?
antdude writes "The New York Times' Well blog reports that 'for some time, researchers have been finding that people who exercise don't necessarily lose weight.' A study published online in September 2009 in The British Journal of Sports Medicine was the latest to report apparently disappointing slimming results. In the study, 58 obese people completed 12 weeks of supervised aerobic training without changing their diets. The group lost an average of a little more than seven pounds, and many lost barely half that. How can that be?"
Your body is not a simple machine. How much you eat impacts how much you use; simply cutting calorie intake will just cause your resting metabolism to drop. Worse, you might start metabolizing muscle.
Hacker's Diet is the best way to lose weight IMHO. It explains the basics (consumer less calories than you burn), and offers some good strategies for eating and exercise and geeky tools (inlcuding a web-based tracker) to aid in your descent into fitness. I lost close to 30 lbs on the "diet" and while it wasn't painless, it was pretty straightforward. I did gain a good amount back 2 years later when I quit smoking, however.
Dude, I think I can see my house from here.
Muscle mass is a really important point. I don't understand the obsession with weight. I went from 32% body fat to 15% body fat and weighed exactly the same. Guess which one of those left me feeling and looking better?
The researchers in the story ignored all the signs from the last ten years which point to strength training being the most important part of a regimen designed to reduce fat. When you do cardio (especially that slow, "fat-burning" cardio), you burn a few calories, and when you step off the machine, you're done. When you train for strength, you burn fewer calories, but your body spends the next twenty-four hours burning extra calories trying to repair the damage you've done. Doing anaerobic / aerobic intervals on a cardio machine has a similar effect, and when you put the two together, you really shed the fat.
You also need to watch your food intake so that your insulin levels stay as constant as possible. That means eating difficult-to-digest (generally "whole") foods instead of processed ones. Your body isn't just a black box. Eating some amount of calories in oatmeal and eating the same amount in breakfast cereal will have different results: your body works harder to digest the oatmeal so your metabolism is higher, resulting in lower total calories; the added fiber changes how your body digests the other food in your digestive system.
Cutting calories is a myth. In fact, while losing about 20kg of fat and putting on the same amount in muscle, I ate more than I had eaten before I started the program. I ate more. I exercised more. The ratio of calories coming in to those going out probably didn't change, but that increase in the total drove my body into overdrive and tricked it into ramping up my metabolism even further than the exercise amounted to.
Put identity in the browser.
The thing about exercise is, until you get to the point where you are pushing yourself to the limits you wont see drastic results. Most of the obese people I see in my gym spend half their time sitting around, or cycling on the lowest level while reading a magazine.
The folks in this study were under close supervision, exercising fairly intensely. It's fun to trot out your favorite lines about exercise but that's not really applicable here.
The majority of fat gain as you get older, is due to deterioration of muscle mass leading to a lower resting metabolic rate. Having muscle helps keep the weight off. As well as reduces the risk if impact injuries and helps actually doing things.
Aide-toi, le Ciel t'aidera - Jeanne D'Arc.
That's your problem right there. Let's see:
Fat is a long term storage form of energy. Everything (proteins, glucose) can be converted to fat, but fat cannot be converted back to glucose (unless you count the lone glycerol molecule that holds the 3 fatty acids together on the triglyceride). It's NOT a reverse reaction. Thus the problems begin. It's easy to make fat, and hard to get rid of it.
So how is exercise supposed to get rid of fat then? Well, fat CAN be converted to acetyl-COA and shoved into the Krebs cycle. Only the Krebs cycle is an AEROBIC process and takes place in the mitochondria, not in the cytoplasm of the cells. Aha! Problem #2. Sedentary people have fewer mitochondria than athletic people. Therefore their ability to "burn" fat as acetyl-CoA is limited. An athlete can burn fat just as efficiently as glucose, the only difference being he'll lose out on the couple ATP from glycolysis.
So you need mitochondria, in quantity, to burn up acetyl-CoA and therefore fat. If you don't get rid of the acetyl-CoA somehow, the whole catabolic process starts backing up. How do you obtain mitochondria? Increased exercise - over a sustained period. 12 weeks is hardly enough to increase the number of mitochondria in your muscle cells, much less expect them to burn through a dozens of kilos of fat. But the title of this article is misleading - according to the study the cited article is based on -
Mean reduction in body weight was -3.3 ±3.63kg (P less than 0.01). However, 26 of the 58 participants failed to attain the predicted weight loss estimated from individuals' exercise-induced energy expenditure. Their mean weight loss was only -0.9 ±1.8kg (P less than 0.01). Despite attaining lower than predicted weight reduction, these individuals experienced significant increases in aerobic capacity (6.3 ±6.0ml.kg-1.min-1; P less than 0.01), decreased systolic (-6.00 ±11.5mmHg; P less than 0.05) and diastolic blood pressure (-3.9 ±5.8mmHg; P less than 0.01), waist circumference (-3.7 ±2.7cm; P less than 0.01) and resting heart rate (-4.8±8.9bpm, p less than 0.001). In addition, these individuals experienced an acute exercise-induced increase in positive mood.
So they ALL lost weight. Only some (probably cheated on their diets/lied about their original diet) lost LESS weight than others. Continuing the exercise for more than 12 weeks would probably have caused further reduction in weight. I don't know HOW the submitter can turn that into "Why Doesn't Exercise Lead To Weight Loss?". Oh yeah, but this is slashdot- news for nerds. This site should be renamed to "Slashdot - news for trolls: engage critical thinking now".
Seven puppies were harmed during the making of this post.
No it isn't and you are posting potentially harmful information. When your body goes past a particular point of calorie reduction, it starts metabolising both its fat reserves and underused muscle. Your body doesn't know how long the "famine" will last. If it burned away all the fat first, then at the end of that process it would have a great load of expensive to maintain muscle for little benefit. If you lose your job, you don't wait until you've used up all your savings (fat) before you start cutting down on unnecessary spending (muscle that isn't being used a lot for exercise). Instead, you are more careful with your savings and you cut back on spending. Do you see?
If you severely cut back on calorie intake (around 15% or more below what you need for maintenance) and you're not offsetting muscle loss with exercise, you lose muscle along with the fat.
The rest of your information is hopelessly out of context. Don't advise people on health matters when you don't know what you're talking about. It's not like talking misinformed crap about Linux or Microsoft. It can harm people's health.
Aide-toi, le Ciel t'aidera - Jeanne D'Arc.
That stuffed belly look is the end-game of starvation, don't be fooled. That woman with the obese look isn't obese, her body has started breaking down connective tissues which leads to sagging skin and distended bellies.