Regardless of where you derive your energy source (and they'll be arguing this until the cows come home), you need to burn it off. Simple carbs, complex carbs, fat, protein; to my knowledge this is the order in which it gets burned off for fuel.
Most people just do not find the time to exercise. Guilt has them parking further away and taking the stairs at work and maybe one forty-five minute workout on the weekend. That will not do. Your sedentary job will not allow you to loose weight. And if you work more than eight hours a day, you don't stand a chance.
More physical activity, less fuel of choice, none after 7PM. Not that I've been able to follow it, but that's my model.
This is an interesting old thread from another forum:
http://web.archive.org/web/20090205123104/http://magicbus.myfreeforum.org/ftopic846-0-asc-100.php
Someone experimented by trying to deliberately overeat a high fat, very low carb diet for 30 days, without doing any exercise. He didn't gain a single pound in weight. Here are some examples of what he ate:
Day 1
2 cups heavy whipping cream
3 raw egg yolks
7 Tbs butter
5 mugs coffee
1.26 lbs. ribeye steak, nearly raw
2 more ounces heavy whipping cream
4260 calories
423g fat
6g carbs
122g protein
Day 3
2 cups heavy whipping cream
3 raw egg yolks
12 Tbs butter
1.24 lbs. ribeye steak, nearly raw
1.74 pounds boneless country style pork ribs, nearly raw
6423 calories
604g fat
1g carb
252g protein
Day 29
15 ounces boneless country style pork ribs, nearly raw
3 eggs, fried in butter
1 pound boiled shrimp
5 Tbs butter
2237 calories
173g fat
5g carbs
157g protein