http://www.thelivinlowcarbshow.com/shownotes/

http://sparkofreason.blogspot.com/2008/06/energy-regulation-1-do-calories-count.html
http://sparkofreason.blogspot.com/2008/07/energy-regulation-2-appetite.html

The key question raised by your response is whether or not the “conscious mind” can override other parts of the brain. The former is a much more recent evolutionary adaptation than the autonomic nervous system as well as the hormones involved in energy balance. I’ll grant you that it’s an open question, but I think it’s more reasonable to believe that the cerebrum evolved to serve the rest of the brain, not the other way around.

Squirrels get fat because their hormones tell them to do so at a particular time of year. If you take squirrel in captivity, it will not get fat in the spring, regardless of how much you feed it. It will stay fat in the winter, regardless of how much you starve it, to the point of digesting it’s own heart muscle leading to death.

I strongly suspect pet obesity (like human obesity) is much more a function of what we feed our pets. For instance, my dog was getting fat and diabetic. The number one ingredient in his food: corn starch. Corn doesn’t grow wild, so clearly was not on the evolutionary diet of dogs. I switched him to all raw meat and a healthy dose of bacon fat, and he dropped 20 pounds. The difference in activity (how much he runs/jumps around in the backyard) is all of his volition, i.e. I didn’t take him out and run him more often. It occurred spontaneously.

Since energy regulation runs the show, I believe it makes more sense that behavior is a product of the energy regulation system, not the other way around. Behavior leading to unhealthy states (like obesity) would thus imply a malfunction of this system. We certainly see this in obvious disease states in humans, like Cushing’s disease and insulinoma.

Unlike animals we have a fairly complex social and cognitive organization. We have emotional and social associations with food as well as social rituals (e.g. birthdays) and structures (e.g. given mealtimes). So, laid on top of all the chemical processes of actual digestion and assimilation are chemical processes of cognition and consciousness. It’s not accidental, I think, that neurotransmitters such as serotonin and dopamine are also involved in regulation of food intake and appetite.

In general terms humans evolved to function with limited and random food availability. This food was higher-fat, largely animal based, higher-fibre, often scavenged and certainly seasonal (where applicable). We also evolved to work for our food, and probably walked several kilometres every day. So we were probably very self regulating too, given the right balance of nutrients and appropriate activity levels. We just don’t look self regulating now because our physiology is a mismatch for our environment and modern nutrition.

Another point to note is that in fact, pet obesity is a growing (pardon the pun) problem. Inactive owners produce inactive pets. Dogs and cats didn’t evolve to sit around small apartments. Not all animals are self regulating. There is individual variation at both the organism and species level. I knew a dog that would eat kibble pretty much until it exploded. It would eat everything else too, including (one year) an entire giant bar of Toblerone, complete with cardboard and foil wrapper.

What keeps animals generally self regulated in the wild is food availability and other environmental considerations such as travel, weather, etc. And, when food is easily available, animals do get fat. (Think about pre-hibernating period. The squirrels look like furry basketballs.)

Finally, animals also have different body fat than we do. Rodents, for example, have much more brown fat than we do. Brown fat is a form of adipose tissue that is involved in thermogenesis, and behaves differently than white fat. Thus, this affects animal metabolism as well. Babies have brown fat, as do adult humans, but as we grow from baby to adult human we lose nearly all of it. There is some individual variation in brown fat, and apparently around 5% of adults do retain a notable amount of it.

Could you explain how total calorie balance is regulated at the cellular level? In particular, I’d like to know how and animal like a dog, given an ad libitum diet of their naturual diet, avoids obesity without the ability to count calories. Thanks!

http://www.scribd.com/doc/6299194/Hunter-Gatherer-Nutrition

Grains are largely absent. Note that these are “whole” foods, so I left off things like breakfast cereal.

I haven’t been able to find any clinical studies that show any health benefit to fiber as an independent variable, e.g. replacing high-fiber foods with meat. The positive results seem to come by replacing refined carbohydrates with whole food sources, which counfounds the cause (is it less refined carbs or more fiber?) If you know of other studies, I’d be very interested. Thanks.