Holy crap, your body evidently does undergo internal changes if you’ve lost a lot of weight! I think I had heard it mentioned before that everyone has a ‘set point’ weight, the weight your body wants you to be. But I wasn’t sure if this was for real or just another fat person’s excuse like “I’m just big-boned” or “I have a slow metabolism.”
Well, according to a genuine, fancy-educated, doctor, Rudolph L. Leibel, head of Molecular Genetics at Columbia Medical School, it’s true. This post at 3fatchicks.com explains it in English. Basically, if you lose a lot of weight, your metabolism when you exercise will be only 80%-85% of someone of the same composition who never lost weight. This is because your body wants you to gain weight. Inversely, if you were to gain a lot of weight, you would start burning 15%-20% less calories when you exercise as your body attempts to lose weight again.
So, if a never-been-fat person and a person-who-lost-100-pounds of the same height, weight, and gender were to both run a mile, the previously-fat person would burn 15%-20% less calories than the never-been-fat person.
It should be noted that this decrease or increase in efficiency only occurs during non-resting energy expenditure. There are evidently three ways humans expend energy:
1) Resting Energy Expenditure – The energy you use just sitting around watching TV
2) Thermic Energy Expenditure – The energy you use to digest food, like that bag of popcorn you were chomping on while you were watching TV.
3) Non-Resting Energy Expenditure – The energy you use walking to the TV when you can’t find the remote. Damn it, where is the remote!
So, the old “I have a slow metabolism” excuse is only half true. I suppose the real question is how much your set point is affected by your genetics and how much of it is your environment.
As you have probably already guessed, all this could explain why people generally have no problem losing weight, but almost always gain it back. Your body actually works against you. It’s quite possible that reduced obese people are miscalculating how many calories they are burning during exercise and may be taking in more calories than they burn without even knowing it.
So, once I hit my goal weight it looks like my body is going to be just a bit fucked up. Joy! At least I know about it now. If I have to eat 15% less or run 15% farther than everybody else, so be it. It’d be nice if they could just figure out how to fix this problem though. They’re evidently trying stuff with leptin, the chemical that regulates hunger and is lower than it should be in reduced obese people.
I find it fascinating that such ground-breaking and important research is happening right now. There’s some person in a lab somewhere who as I type is doing experiments on fat rats. Go science geeks! You figure in a hundred years or so they might have this obesity thing figured out. Then our great-grandchildren can laugh at us and all the silly ideas we had about weight loss. Jerks. It’s not our fault we know almost nothing! We didn’t even discover leptin until 1994. Hell, the World Wide Web has been around longer than that.