This may start out sounding like a Car Talk question, but I have a disagreement with my husband about perceived temperature that I am hoping my fellow PH's will help me with, namely I am always hot and he cold. This means fighting over the thermostat setting, amount of covers etc... (He prefers to sleep in 75 degrees, while I want the window open and 60 degrees). We both exercise a lot, so it isn't a circulation issue on his part (See I am assuming he's the one with the problem). It has always been this way since we met as vegetarians 18 years ago (so it isn't likely a hormonal issue on my part, nor a reflection of my recent move to paleo). He is a pescetarian who has never eaten meat, even as a child (due to inherent disgust). I have eaten meat since pregnancy ten years ago. He is fairly lean (not skinny, but well-muscled) while I an a life-long fitness buff with probably 23-4% bodyfat.
He says he has a high-metabolism because he is slim and has only ever put on weight during a period when he drank a lot of beer. I say I have a high metabolism because I am consistently warm. If metabolism was just measured by body-fat %, that would mean most women would have lower metabolisms than most men. Is this true?
My sister has been vegan for 6 years and has a very hard time regulating her body temperature. My dad has been vegetarian for 40 years and always has cold hands and feet (for him that might be poor circulation though). The first article i cited links to a journal where they conclude that low protein diets (most protein in plants is bound to cellulose and not as bio available as meat protein, you can look up the boavailability of proteins on nutritiondata.com) result in a different temperature regulating response in rabbits. #3 shows thermogenesis is increased 100% on a high protein diet.
I've noticed that I used to have trouble regulating my body temp before I went paleo and introduced more meats, like steak. I grew up from 8-19 on a low protein veggie diet, and me and my sister used to both be sensitive to temperature changes but that's changed this winter. I don't think being warmer or thinner necessarily facilitates a higher metabolism than the other though.
I don't know about being warmer, but it's probably not being thinner. Contrary to popular belief, fatter people usually do not have lower than average metabolisms and in fact, they frequently have higher metabolisms:
Being thin however does not appear to follow a very clear trend in this regard. The metabolic rate of thin people varies heavily depending on the person/group, everything from higher to lower than average, at least according to my reading.
I don't have any studies to point you towards, but I am interested in reading the answers to your question. I have been a vegetarian (though an occasional consumer of fish and seafood) since I was a teenager (about 15 years) and have only recently (the past few months) started adding some high-quality meat to my diet. I am quite thin (BMI of 18) and I also have difficulty regulating my temperature. I am always chilly and like your husband I prefer to sleep in a very warm room. My husband is not a vegetarian, though he has eaten mainly vegetarian meals (because I've cooked them) for the last 9 years. He is also quite thin (6'3" 170 lbs) and walks around all winter in a sweater while I'm in my parka. We are both moderately active.
When I started to eat paleo, I quickly lost about 5 pounds despite eating what seemed like a lot of fat and certainly enough calories. I struggle to gain weight without eating a lot of carbs. Since I'm naturally thin I've always thought I must have a fast metabolism, but I'm not sure about the temperature question. I imagined that if I gained some weight I would feel warmer, but my husband doesn't have much extra fat and never feels the cold, so I don't know.
Gary Taubes, Mark Sisson, and unlimited fats 16 Answers