I love exercise when I have too much energy and for getting out of the house. But yeah for loosing weight? I wouldn't think so.......unless you want to be one of those super skinny celebrities that eat nothing and wrok out like crazy.

Dont get me wrong I like skinny, but I remember the term "skinny fat" where you are thin but have some fat (ass/tits/hips).

It might not make me thin (I already am) but boy, do I love exercise. Riding my bike to work, longer rides when I can, playing squash. The physical feeling of being in my body, using it; even the slight pain when I overdo it, sweating, panting, the competion, the fight - I just love that feeling.

And even though I do feel hungry from it, I lose interest in sweets. The better shape I'm in, the less I crave for cake and candy and chocolate.

Once upon a couple lifetimes ago, thanks to the aftereffects of 9/11, I spent four months slinging satellite dishes at the sides of houses in Michigan.

Which meant I was getting exercise. Lost 7 pounds (from 5'10", 160#).

Sorry, I don't buy it. There are two important effects of exercise on weight loss:

1. Exercise uses energy, your body gets energy from food. If you eat the same amount of food, using more energy will help you lose weight. The thing is: exercise alone is not enough. You can't say "I went jogging, I deserve an extra quart of ice cream". To lose weight, exercise *and* watch what you eat.

2. If you lose weight without exercising, your body will eliminate unused muscle as well as fat. A 150lb woman can be fit or fat. Exercise uses your muscles, meaning that your body will lose fat.

The article says "does not support the use of exercise as a primary tool for getting thin". This does not mean that exercise is unimportant for weight loss, simply that exercise alone is not the answer.

Weight loss: consume less energy than you burn. Exercise helps you burn more energy.

The operative word here is "primary". Of course, if you are not eating right and drinking lots of water, no amount of exercise is going to make you skinny.
I didn't start working out til I hit my goal weight, just walked a lot. After I hit goal, I added body sculpting and water aerobics. I wanted to tone what I had, not lose more.
After I started working out, I had to eat more, or I started losing weight again. I eat like a horse when I'm working out religiously, not so much when I slack.

More than a few years back I was a member of an amateur bike racing club. My first "lesson" was just how hard you have to work to be competitive. Imagine pedaling as hard as you can, on the flat, and going as fast as 22 - 24 mph. If you hold this speed, you can burn as much as 1,000 calories/hour. Putting more numbers to this, you are continuously turning the cranks at 100+ revs/minute with the big front sprocket and maybe the 2nd or third smallest gear on the back. This is not something you "decide" to do. It take years of training and effort to hit this level. To hit this level is as much a mental as a physical exercise. Where mots folks are please to hit low 20's in a sprint, in racing, you must HOLD a sprint, for hours.

More than a few years back I was a member of an amateur bike racing club. My first "lesson" was just how hard you have to work to be competitive. Imagine pedaling as hard as you can, on the flat, and going as fast as 22 - 24 mph. If you hold this speed, you can burn as much as 1,000 calories/hour. Putting more numbers to this, you are continuously turning the cranks at 100+ revs/minute with the big front sprocket and maybe the 2nd or third smallest gear on the back. This is not something you "decide" to do. It take years of training and effort to hit this level. To hit this level is as much a mental as a physical exercise. Where most folks are pleased to hit low 20's in a sprint, in racing, you must HOLD a sprint, for hours.

I remember the term "skinny fat" where you are thin but have some fat (ass/tits/hips).

I think that used to be called "healthy".

Exercise uses energy, your body gets energy from food. If you eat the same amount of food, using more energy will help you lose weight.

Yes. Best of luck doing that, tho.

If you lose weight without exercising, your body will eliminate unused muscle as well as fat.

Umm, no.

Stored fat is much more easily converted to energy, and is metabolized first. Once you've lost most of your fat will your body expend the additional energy necessary to burn muscle.

That can be considered a starvation diet.

Some people exercise because they have to (like my colleague who can't sit still for more than 30 min before his leg starts twitching compulsively). I am not that person. I exercise because I live in one of the great outdoor playgrounds of the world and it's a waste not to get out there into it.

Now that Amy has posted another diet post, I am going to use the comments to comment on stuff I have been mulling over for a while. This "exercise doesn't help lose weight" is just wrong when over-applied. Appetite doesn't go up in perfect proportion to the calories burned for real exercise (a 1 mile run isn't exercise). If the exercise is only a few hundred calories a day, it might, but it isn't a straight-line relationship. I burn about 1200-1500 calories a day training and I do not eat 1500 calories a day more to make up for it. Every athlete gains weight when they are injured and loses it again when they are back at it. Taubes jokes about "a mile of running only burns 100 calories". Well, yeah 1 mile is like nothing. I was once injured and gained up to 180, training hard I weight 160.
I am 6'4". 160 and, unlike Paul Ryan, really 6% bodyfat. I eat enough carbs to replace my glycogen each day and run 80mpw.

I switched from a diet of about 60% carbs to one of about 30% and my weight didn't change at all (thought I still prefer paleo eating for other reasons).

Also, Amy, on the Volek study - something I have wanted to respond to for a while but suspect you won't listen, is that endurance athletes do indeed need carbs and the Volek study you sent me didn't replicate what elite endurance athletes actually do. You CAN fuel a slow run/ride to exhaustion on fat - the body has enough fat to fuel hours and hours of exercise at a pace that burns 10 or so cal/minute (cycling burns fewer cal/minute than running). The problem is, it can't provide calories fast enough for athletes who are so fit that they can burn 20 calories/minute - elite athletes can run/ride for a hour at 90% of max HR. You have to dip into glycogen to provide that rate of calorie demand. On a hard run, about half of one's fuel comes from glycogen because it has to - fat (while there is plenty of it available for fuel) can't be metabolized fast enough for the demand. On a slow run, you can burn almost all fat.

And I promise you, morbidly obese people do indeed eat too many calories for what they burn and if they ate 6000 calories a day of no carbs, they would be obese. Spend some time in my native South and you will see what I mean. You brag about eating bacon (I myself eat about 3 boxes a week) but it just ain't that caloric - a 12oz box is only 470 calories. I would wager your calories per day are less than 2000.

Taubes is absolutely correct that sedentary people need few if any carbs and would be leaner on the same number of calories without the troublesome issues of insulin promoting fat storage (since they never burn glycogen) and he is right about the ridiculous demonization of fat. And he is right that eliminating carbs will enable your body to regulate better some degree of calorie surplus. And a lower carb diet will promote more satiety so it won't be a problem for most people (it is insanely hard to overeat when you aren't eating any carbs). But you still can't eat a huge calorie surplus of thousands of calories and stay lean just because it is carbs and your appetite won't go up in tandem with exercise demands of 1000+ calories a day. And endurance athletes (not gym rats, but people who train like elites) play by a whole different set of rules. See Dr. Eades here:

http://www.proteinpower.com/drmike/fast-food/the-dean-karnazes-diet/

The correct diet is right carb (which is much lower than most people think, and may be none if you are sedentary). Not only the right proportion (cyclists have been into 40/30/30 for at least 25 years) but the right kinds of carbs (for most people, this means no wheat, no whole grains, but fruits and root vegetables if you have an exercise-induced carb demand).

See also Dr. Cordain on why athletes are different:

http://www.amazon.com/The-Paleo-Diet-Athletes-Nutritional/dp/160961917X/ref=sr_1_1?ie=UTF8&qid=1348071579&sr=8-1&keywords=cordain+paleo+athletes

And, of course, maybe 30% of the population can get away with a higher carb diet (usually natural ectomorphs like myself) and not experience insulin resistance or ever develop it. Like I said, I was 160 eating pasta every day and drinking some soda and I am 160 eating bacon and sausage every day.

Well, it's gotta be a little better than the exercise belt thingie my mother had, where the motorized belt did all the work and you just had to stand there and vibrate and wait for the pounds to fall off!

Oh yes, that worked well. And my dad used to try every new thing, like these "space sticks" of food like the astronauts supposedly ate.

I wonder what happened to the one where they wrap you in plastic and supposedly make you exercise til you sweat off all the toxins and mold yourself into shape for that big wedding or whatever? Haven't heard about it in years. Maybe they finally killed somebody.

Excellent post Brian.

For most of my life I was on a high carb, low protein low fat type of diet and I was waify thin. That all changed with medication I'm taking and my body can not consume carbs. If I stick to low carb I loose 18 lbs in three weeks.

Also asians eat alot of carbs but no sugar/fruit.

Should Americans switch to low carb? Yes! The best diet for optimal health for most is meat veggies with low sugar fruit.

I like activities that involve physical exertion, but I HATE exercise for the sake of exercise. I tried the gym membership and it was horrible. For one, running on the treadmill or elliptical for an hour to burn a few hundred calories just seemed like a complete waste of time to me. For two, I can't focus that much on an activity I care nothing about. I had to have my iPod, my book, a pad to scribble on, etc. to get through the session and finally I just gave up because honestly why would I torture myself that much?

I've started cutting carbs out of the diet (trying to lose the divorce lbs). I've lost 10lbs so far in about a month, and haven't really even been trying. So that's hopeful. I'm still eating carb things here and there, but interestingly enough, I seem to be losing my taste for them. I'll have to avoid Red Lobster though. I love those bisquits.

Dunno Amy.

I lost 30 pounds in 2 months and have kept it off for 2 years simply by going the thermodynamics route. I ran about a 1,500 calorie deficit everyday. Try running that kind of deficit for more than a few days without exercise. Life on 750 calories a day would suuuuck. Even if it's all bacon.

"You can't out-train a bad diet" My high school and college years call bullshit. All those overweight cross country runners out there.

You are like Sisyphus pushing this ball of science up a mountain of a priori knowledge. You may prove to be right on the biochem but it doesn't explain the observed phenomena.

No one will ever take my hour a day at the gym from me. Endophin highs are the best! Plus, there's a world of difference in weak flabby size 6 and tight toned sz 6.

I *might* run if a murderer was chasing me. I burn a LOT more than a couple hundred calories in my hour, though.

No one's ever taking my Red Lobster biscuits, either, although they're about a twice a year treat.

The thing is, that exercise is a great thing. An overweight person who exercises is in much better condition than a skinny person who doesn't. But in their weight loss zeal, the food grabbers are *dis*couraging people from getting exercise. By saying exercise is the key to weight loss, they get people to (1) exercise, (2) not lose weight and then (3) give it up. So they are worse off.

As an avid weight lifter who has seen the changes in my body firsthand, I am highly skeptical about these studies for a number of reasons:

1) Not all forms of exercise are created equal. A 20 minute session on the elliptical 3x/week is not going to produce the same results as 5 days/week of pumping iron, or training for a marathon, or completing an intense workout program like Insanity. Most people who are serious about working out already know that steady state cardio is minimally effective, yet these studies rarely examine any other forms. This is the equivalent of studying the earning power of a college degree using only Gender Studies majors. Do a study on the effects of a 12-week heavy weight lifting program then tell me that exercise is useless.

2) Weight loss is only part of the picture. My maxim is diet to lose weight, exercise to change your body and maintain your weight. While exercise might not make the number on the scale go down, the right type of exercise is key to decreasing your body fat, looking better, getting thinner, targeting problem areas, and shaping your body into the look you want. Someone who works out effectively will appear thinner and wear a smaller size at any given weight. And they just just plain look better. But that difference won't show up on a scale and I doubt it's been effectively quantified and measured.

3) Humans are not lab rats. The type and quantity of foods that we eat is determined by a number of variables beyond merely our hunger levels, and exercise can have a positive impact on these variables. Sure an hour at the gym might make you hungrier, but that's an hour where you're not stuffing your face in front of the TV. And you skipped the bowl ice cream in anticipation of your workout. And you feel good about yourself afterwords so you make a healthy dinner instead of going to McDonalds. So even if the gym session increases your immediate hunger, your net calorie intake is still lower--and it's not like you were eating that crap because you were genuinely hungry anyway. Even if it's a placebo effect who cares as long as it works.

There are probably more objections but these are the major ones. And until I see a study that addresses these variables I am going to take the conclusions with a grain of salt.