Yes, Virginia, Exercise Matters for Weight Loss

I now have three years worth of experience and data to draw on. I also have almost the same amount of data for my partner, who is a PhD biomedical researcher, so as extensive as my data is, hers is even more impressive. From this I make the following observations...

1. My lightly-active TDEE is 2900-ish, confirmed by maintaining maintenance
2. I can do 1600 cal/day (ish) for a max of ~2 weeks before I binge
3. I can do 2000 cal/day (ish) for a max of ~3 weeks before I binge
4. I can do 2700 cal/day (ish) more or less indefinitely (longest streak is 4 months without a binge, and that was holiday-induced)

Now here's the interesting bit. That 2700 calorie "indefinitely" level is fairly constant for a wide variety of activity levels. It works from 3 walks a week right up to 3 runs + a couple of cycles + 2x swimming a week. That's a range of (average) deficits from <200 (ie, basically nothing) up to a deficit of about 600 calories/day.

When activity burn goes above that, I need to compensate. So, for example, at 3000 calories/day I was able to maintain a TDEE of about 3600 cal/day.

The numbers for my partner are different, of course, due to gender/size differences. But the same pattern exists there - there's a "comfortable" level of eating that supports significant deficits IF those deficits are created primarily through exercise rather than through a significant drop in calories.

I'm not going to claim this pattern holds for everyone. I was a high level athlete into and past college, competing at a semi-professional (ie minor league) level. I love playing sports, so it's quite possible I'm predisposed to this kind of "set point". I accept that others may not be - in fact, evolutionary processes being what they are, I suspect others won't be.

NOTE 1: Those who know me here know I'm extremely conservative/correct on exercise burns, compared to what most people are logging for similar activity. I must have hundreds of posts correcting other people's burn claims. So to compare my burn numbers to typical MFPers numbers, double mine.

NOTE 2: I've been on MFP long enough to know there are a bunch of pedantic fight-pickers, so let me say this explicitly: weight loss was 100% determined by caloric deficit. What is under discussion here is the method of creating a long term caloric deficit.