In the abscence of disease, I think that metabolic reserve is largely a function of age. In general, young people can tolerate a lot more dietary abuse without apparent ill effects than older people.

Before I turned 40, I could eat or drink just about anything I wanted, which was mostly a sugary, processed SAD. After 40, I slowly accumulated flab at a rate of 1 to 2 lbs. per year. By the time I was 50, skinny had turned to skinny-fat. Now on a more paleo lifestyle, I'm turning things around.

Matthew, you're intelligent and insightful enough to live healthy while you're young. This should keep you healthy and active for many years.

I too am generally not very hungry. The only way I know when to eat is when I start dragging, both mentally and physically. I never get hunger pangs, which can be a good thing for someone trying to lose weight, but not for me @ 20 years old 5'10 150lbs.

Also, for the people who say they could eat whatever they want before "x" age, it has nothing to do with your age. The rate that your metabolism slows down as you age is in fact pretty small, why you gain weight is because you become less active while still consuming the same amount of calories. Sure the hormonal response to eating a Paleo diet vs. SAD does play a part, but for the biggest factor is energy expenditure if the diet remains the same.

I think I'm mostly in good shape also but my philosophy is eat healthy if you are healthy and eat healthy if you're not. I did slim down and eliminate hypertension (so maybe not so healthy originally) on a high-fat, low-carb paleo diet. Fasting 18 hours a day is practically my normal daily routine now. I've never felt better and don't intend to change things up all that much ever. Keep being awesome!

I had one year where I was slightly pudgy, but I don't have any really dramatic before and after pictures because I guess I have a good metabolism. I'm glad I nipped the slowness in the bud with paleo. When I read some of these stories of people living with diabetes or other serious problems, I'm glad I found this diet when I was 20!

I'm in the same boat as you, man. The closest I ever got to being overweight was last year, my first year in college. By the end of spring semester, I was about 180 lbs. At 6'0", thats not too bad, but I was definitely skinny-fat. Now I am at about 163 lbs., with about 5% or 6% body fat, and I'm much stronger than I was before.

Unfortunately, I'm a very active guy, and fasting just isn't really an option for me. I had tried doing it for a few months, but I just kept losing weight, which I really do not need to be doing. Also, I was afraid it might be affecting my muscular growth. So, while I may skip a meal here or there, I generally try to eat three square meals a day, with protein at each meal, and snacks in between.

Anyways, I'm not eating primal/paleo in order to lose weight, like so many others. I'm doing it to be healthy, to remain healthy for life, for optimal performance, and to support family farms and organic products. There are so many benefits to this lifestyle beyond weight loss. Better sleep, better concentration, improved focus, stable energy levels, better skin and hair, etc. etc. I'm in this for life.

I was originally brought up to eat very little sugar as a kid. My parents have always questioned Conventional Wisdom and I guess their skepticism eventually rubbed off on me. As I grew up and was exposed to more and more of the SAD, my parents added more and more of that into the household and it eventually came to the point where I was pretty much eating SAD on a regular basis. I have to give my mom lots of credit, though. Most of my dinners were home cooked meals which were certainly much better than a trip to McDonald's (and tastier).

My indulgence in the SAD peaked during my Sophomore summer in college (when I was taking classes at the university). I put on some pudge after eating shit food for a long time. My license picture actually shows this still, as a constant reminder. I lost most of it after consistently lifting weights 3 times a week. I've gone paleo mainly just because I want to eat the best diet possible which will let me extend my health as long as possible.

I am 20 and started less than a year ago because of acne. I tried VLC for 2 months and it was not for me, sports performance suffered too much (mainly racquetball, some lifting). Now I feel much better at around 25-30% carbs, mostly coming from tubers and starchy squashes (fructose exacerbates my acne). I am not low carb, but not high carb either. I don't see an advantage to being VLC if your metabolism is not damaged (have not been able to find any research that points to this, for healthy people).

I was never overweight but half a year eating paleo got me into single digit bf% without even trying (I do IF though).

I've been pretty healthy, besides some issues with mild periodontitis.

I started paleo to enhance my fitness training and maximize the results of my efforts.