Redwing said...
Calories in minus calories out equals net calories. Too many, and it's stored as fat. 3600 extra calories is one pound of fat. The math is straightforward.
Let me start by admitting that I don't buy it*, but before we get to that I will suggest a reason that it doesn't matter.
Suppose you are trapped in a garbage masher. Your problem is that the force of the hydraulics is greater than the force exerted by your puny muscles and your fracturing bones. If you could only balance those forces then you'd be OK. Unfortunately, the real solution to the problem has something to do with that lever on the side of the truck.
Excess dietary energy is stored as fat when you eat too much. This is generally true. But there are various controls on the process of converting energy to fat. In diabetics the process doesn't work very well. Any food they eat in excess of their immediate energy needs will simply stay in their bloodstream as sugar, often reaching toxic levels. They have to take insulin to get it converted to fat. On the other hand, people who produce a bit too much insulin tend to store too much energy as fat and their blood sugar drops and they become hypoglycemic. The process of balancing energy vs fat deposition is a homeostatic process that involves appetite, energy expended through thermogenesis, and the storage of excess energy as fat. This process works fairly well at keeping things on an even keel. It only takes a few calories a day plus or minus to make big differences over time. But our weights don't generally zig and zag over huge ranges even if we pay no attention to our diets. On a "western" diet the average adult seems to gain about
a pound a year (ten pounds a decade). That's 36,000 extra calories in 3652.5 days or just under ten calories a day. That means that our bodies manage their energy balance to a precision of around 0.5 percent of total calories. But what about
people who watch what they eat and diet to try to keep slim? Actually, they also seem to mostly wind up gaining the same ten pounds a decade.
I contend that trying to eat less to manage your weight is pointless. You are just struggling with the homeostatic feedback loops that will win in the end in an environment with sufficient food on hand. What you need to do is to try to figure out why your homeostasis is slightly out of whack and I contend that changing the macronutrient balance in your diet is probably the way to do it.
It is true that it takes energy to make a person fat. It also takes food to make a teenage boy taller or a teenage girl shapely. Telling a fat person "Get away from the fridge, can't you see how fat you are getting?" is a lot like telling a teenage boy who wants to be a jockey to get away from the fridge because he is getting too tall or a teenage girl who want's to dance to cut down on her chow because she is up to a C-cup already.
What does seem to work better is to cut out sugar from your diet and if your weight continues to creep up modulate your carbohydrates until your weight turns around.
* While I believe in conservation of energy and everything, I have to admit that when very-low-carb diets work they seem to work better than the appetite suppression or water loss can explain. I am tempted to think that high-energy chemicals are getting out of the system somehow. People on Atkins-style diets excrete ketones through their lungs and this (30-year-old) study on pigs found that pigs on a high-fat diet only digested 75 percent of the available energy in their chow as opposed to 93 percent for pigs on normal chow.
Thermogenesis from the breakdown of a ketogenic diet in an experimental model using swineThere have been studies that pooh-pooh this alleged "low-carb-advantage" but diet research is so tendentious and tribal that I am difficult to convince. But I dunno.