Have you ever heard the analogy that "fat burns in a carb flame?" You can't burn fat without a little carb. I'm gonna guess that the first 20 pounds was easier because you were eating fewer cals, not just eating fewer carbs?
Wilson6:
"You won't find lit on this. Probably take the scientific/nutritional community 10+ years to do a study. If you understand Krebs, fatty acid oxidation, the need for pyruvate to maintain Krebs cycle intermediates and how when they are depleted, fat oxidation slows and ketones increase and ATP production decreases, then it will all make sense. If you don't have a handle on these pathways, then it won't.
Chronic dieting decreases 5' deiodinase activity.
Not to mention that ATP is needed to convert unactive T4 in your liver into active T3..."
MS:
"I also can't imagine anyone ever funding a double blind placebo controlled cross over study of a large number of bodybuilders to address the question of whether a carb inclusive diet is better than a ketogenic diet for fat loss with maximal muscle retention. To me it sounds like this is what you're asking for as "proof". You will find no proof. You will find plenty of people over on the diet board who religiously believe in ketogenic diets for fat loss. The fact is, if calories are below maintenance you will lose weight no matter what diet you use. Obese couch potatoes LOVE Atkin's becasue they can eat all the greasy slimey food they desire, and they are not worried about retaining or gaining muscle. Their appetite dies a natural death as well. They just like to see the scales go down, though as Daeo pointed out, their basal metabolism will also drop from lack of T3 conversion, and heaven help them if they ever go back to eating carbs again. You will find people who adore CKD diets. These are hard core to optimize and follow, and only allow you two intense training days per week. I have known virtually no females who didn't suffer bad rebound fat gain when coming off a CKD, and I don't know of any top level BB competitors who use this diet. The proof is in the pudding as my grandma would say. You will find folks who will drag out references to Inuit Eskimos, epileptic children etc.... as "proof" that ketogenic diets aren't bad for ya. Whatever. I'm a body BUILDER. Bodies are built on carbs. Even the Inuit Eskimos had a very high protein intake most of the year, a lot of which their body no doubt converted to carbs to build muscle necessary for their survival. It seems an expensive way to get carbs from my perspective (unless you live in the furthest reaches of Alaska). I haven't met any epileptic kids on keto diets who were bodybuilders either (but then again I haven't met any epileptic kids on keto diets)."