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.

http://www.medicinenet.com/emotional_eating/article.htm

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”.

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Thanks

I’m sure this has already been worked into the Aquatic Ape Theory, but just in case, I may send Elaine a memo…

…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.

Greg:

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]

‘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.