Learn all about fat. Get depressed.

kw: book reviews, nonfiction, physiology, fat, weight loss

I have known for a long time that for many of us in affluent countries, weight management is a fierce challenge. We can see this from the very existence of Weight Watchers, Nutrisystem, Jenny Craig and literally hundreds of other clinics, systems, and plans, and the $60 to $150 billion that Americans spend on weight loss proves it. If weight management were easy it would be cheap, and we wouldn't need all those clinics and "life coaches" and the rest.

Now we can learn in great detail just what we are up against…if we really want to know. I suspect many folks don't want to! I am not sure if I am happy about knowing, either. Like it or not, I just finished reading The Secret Life of Fat: The Science Behind the Body's Least Understood Organ and What it Means For You, by Sylvia Tara, PhD.

You read right: Dr. Tara calls our fat system an organ. It is the largest and most complex endocrine organ in our body, except perhaps for a very few people who cannot deposit fat and as a consequence must eat tiny meals two to four times hourly to stay alive and comparatively pain-free. Do you think you'd like to be truly fat free? Without a system of depositing fat, which our liver and other organs produce continually, the blood gets milky with circulating lipids that just go 'round and 'round until they are used up by metabolic processes. Heart attack at a young age is the typical fate. People with this affliction who try to eat "more normally" wind up with painful lipid deposits in the skin, rather than normal layers of healthy fat, and in either case they look like walking skeletons, like it or not.

Fat does a lot more than regulate our energy stores. As an endocrine organ, it communicates with the rest of the endocrine system, regulates appetite and metabolism, determines our fertility (or its lack), and stands ready to help us stave off a famine. In babies, the "brown" and "beige" varieties of fat produce extra energy to keep the little body warm. When you have the weight-to-skin area ratio of a house cat, but no fur, you need to produce a lot more energy per pound to keep from freezing to death at "normal" temperatures in the 70's (or the low 20's in Celsius). A strange therapy that turns some "white" fat to "beige" fat is being tested to shift people's energy balance for weight loss. It promises to be even more costly than staying at a Mayo Clinic Weight Loss residence.

You may have heard of ghrelin, leptin and adiponectin. These are just three of the signaling molecules that make us hungry, or not. Leptin turns down our "appestat", the others raise it. Several other signals shift our cravings here and there. Others "tell" fat to deposit itself in our subcutaneous layer ("safe" fat) or viscerally ("dangerous" fat). Guess what can shift all of these in a healthy direction? Exercise. Lots of it. Nothing else is as effective.

Also, as we are only recently learning (partly because of a genuine conspiracy carried out 50 years ago), sugar is much more of a culprit in making us fatter and making that fat less healthy than we used to think, as compared to dietary fat. To be clear, trans fat is truly evil (and all of us who grew up eating Margarine rather than butter must shed a tear here), and also, while saturated fat is a little better and some is actually necessary, saturated fat has to be balanced with the mono- and poly-unsaturated varieties or it does cause problems. But excess sugar is the worst, and sugar substitutes, oddly enough, are almost as bad, because the insulin system kicks in when we taste sweetness, regardless of source. An insulin spike causes fat to be deposited.

During my last ten years working, I got in the habit of drinking about a liter of sugar-free cola daily (Pepsi Max had the best taste). Upon retirement I stopped drinking soda almost entirely, and lost 15 pounds. At first I thought the weight loss was because I was under much less stress; chronic stress also causes weight gain. But now I think it is probably at least half due to stopping my soda pop habit.

After nine chapters of the science of fat—and fascinating science it is—the last four chapters are the "how to" section. The author is a woman, she is descended from an ethnic group in India that endured repeated famines for millennia, and both of these work to make her metabolically fitted to gain weight and hold it, waiting for the next famine. She has also done a certain amount of yo-yo dieting. Guess what? If you have never been overweight, you have a metabolism that matches the calculations at sites such as the Basal Metabolic Rate Calculator. There I find that my basal metabolism is about 1,750 Cal/day, with a dietary intake need of between 2,400 and 3,000, depending on how active I am. Were I female, these numbers would be 1,550, 2,050 and 2,650 (Note: I rounded the numbers from the overly-exact calculations. Also, when I write Calorie, I refer to kilocalories. The calorie of physics is 1/1000 of a Calorie).

What if you have dieted, and regained your weight? Your fat system changes, permanently, so that maintaining the weight now requires fewer Calories, a lot fewer (20-30%). So, you struggled with a 1,200 Calorie per day diet and lost 25 pounds. You used to eat 2,400 Calories daily. If you go back to a 2,400 Cal/day diet, you'll gain it all back, and then some. You'll even gain it back, more slowly, at 2,000 Cal/day! If the BMR Calculator says your dietary need at the weight you want to maintain is 2,250 Calories, you'll actually now barely be able to hold the new weight at 1,700 Cal/day. That is a cruel fact of weight loss-and-regain.

Chapter 12 is titled "Fat Control II: How I Do It". Dr. Tara eats no dinner. Ever (hardly ever!). She chronicled, almost pound-by-pound, how she lost a certain amount of weight over about a year, and how she did it using a "partial fast" of no food intake for 18 of the 24 hours a day, and small high-fiber meals in that 6-hour "eating window". She also boosted her activity level, mightily. She recommends 5 workouts per week of 45 minutes' duration, sufficiently vigorous to make us sweat and have a hard time talking (none of this treadmill-walking while holding a conversation on the phone!).

I decided to check something. I used the short-form Longevity Calculator at Wharton twice, making one change between. The first time, I put "1-2 workouts per week", the second "5+ workouts per week". My life expectancy in the first instance is 91, and in the second 92. In either case, the tool reports that I have a 75% chance to live beyond age 84. Going back and changing activity to "rarely", returned a life expectancy of 90. Hmm. I am 70 now. If I hold up, and am able to do those vigorous workouts 5x/week, I'd spend an extra three hours weekly working out. That is 156 hours yearly or, in 15 years (until age 85, when I'd probably have to slow down!), 2,340 hours. My waking hours in one year are 6,570 (I sleep 6 hours on average, in spite of trying to stay abed longer).

So I can gain another year of life if I spend about a third of it working out. Would I be healthier? Certainly, as long as I don't tear up my body doing all those workouts. I'd have to get into it gradually. So it is likely that those 15 years would be pretty good ones. On the other hand, it would have to go hand-in-hand with less eating, meaning I'd be living with being chronically hungrier. That is not an easy choice, but this is the kind of cost/benefit analysis we need to do. Unless the FDA approves an economical form of Leptin treatment to help us manage appetite, it's the best hope I have of being svelte again. That's mildly depressing.