This is a pretty good description of the experience people go through in trying to maintain a constant body weight. I've spent the last few days reading weight-oriented blogs and websites, and of course I've experienced my own struggle to maintain a constant weight. At the bottom of this post, I've linked to some of the most interesting blogs and websites.
Based on what I've learned so far, it looks as though there are a few people who are genetically predisposed not to store fat. These people would be in big trouble if they were in a situation where food was not always available, but they do well as long as there's plenty to eat. It is possible to be born with a genetic tendency to be thin but to be infected by a virus, such as the AD36 adenovirus, which causes the body to create fat cells. Between genetics and infection, something like 80% of people tend to gain weight when we eat regularly. Of these people, some are able, through constant vigilance and deprivation, to lose and/or maintain a constant weight.
Until fairly recently, few people had a constant source of food. For people who are subject to periods of food scarcity, fat cells are literally life-savers. Those fat cells are like having a readily available cache of food that doesn't spoil or become infested with insects.
It is possible for one to eat so much in one sitting that one's stomach bursts, but in all but a very few cases, this does not happen, because eating is regulated by hormones that cause a person not to be hungry any more when the blood sugar reaches a certain level. Hormones also drive a person to eat when the blood sugar level falls. These hormones seem to have a "memory" of a person's highest weight, so when person loses weight, the hormones drive the person to eat enough to regain the weight. When people lose weight, they lose both muscle and fat; many people (especially if they are 40 years or older) add more fat than muscle when they regain the weight they lost.
The body's reaction to weight loss would be likely to prolong one's life in a situation where food is not always available -- which would have been the condition of most people who have ever lived. Therefore, it's not accurate to think of it as a flaw, and it's not appropriate for people to hate their bodies for "betraying" them by driving them to gain weight.
Many people do appear to hate their bodies, or even themselves. They believe that their inability to lose weight or stabilize their weight at a certain point is due to weakness or a moral defect of some sort. Some people accept their weight, which is fine to a point. But there is a point at which a person's stored fat begins to interfere with the normal function of their bodies. Walking becomes difficult; running impossible. Weight-bearing joints such as knees deteriorate more rapidly due to the stress of carrying more weight than they were meant to carry. The heart has to work harder to service the larger bulk of the body (but the heart also grows larger, so this may not actually be a health problem). Meanwhile, the hormones keep on doing their job -- the drive to eat is almost at inexorable as the drive to breathe.
I saw many blogs that were full of hope to begin with but ended abruptly after an initial weight loss followed by a gain. Then there were the very rare people who managed to lose significant amounts of weight (up to 1/2 of their initial weight) and keep the weight off. One of these people describes weight maintenance as a part-time job (Debra's Just Maintaining). In general, there appears to be a rift between weight-acceptance people and weight-loss people. Debra's philosophy is that she could easily gain weight again (for example, if she were unable to do the relatively high level of exercise required to keep the weight down), and if that were to happen, she doesn't beleive she would deserve self-hate. I agree with her, and the research supports her -- maintaining weight after weight loss requires far more exercise than maintaining one's highest weight. As part of the body's fight to keep itself alive in a sitatuion of perceived food-scarcity, muscles function differently after weight loss. They become more efficient, can perform more on a given amount of fuel. So exercise that requires 100 calories when done by a person who has never lost weight might require only 75 calories after weight loss. This is great for a person stranded in the woods with nothing to eat but lean meat, insects, and plant matter, but not for a person who has ready access to concentrated sources of carbs and fats.
Food is at the center of almost every special event and celebration of friendship. This is not surprising, given that most people who have ever lived went through regular periods of food scarcity. It makes it really hard for people who are trying to lose or stabilize their weight. Given the statistics, it's completely normal to gain weight. The exceptional people are the ones who don't gain. Therefore, it's not accurate to refer to low body weight as "normal."
What to do when "normal" is not healthy? Some people recommend support groups, which seem to work well for short-term weight loss. But people who get the weight off and keep it off seem to be motivated more from within themselves, like artists.
I myself have 4 motivations:
(1) my knees are shot, and I want to avoid knee surgery -- this is my main reason for wanting to lose weight. My knees function a lot better when they have less to carry;
(2) I'm getting old and do not want to accumulate great masses of belly fat, as my mother has done;
(3) I started sewing and became interested in fashion, and many of the garments I'd like to make look better on slim bodies than on larger ones;
(4) I feel better when I eat a diet that consists mostly of fresh veggies, fruits, fish, whole grains, seeds, and nuts; this same diet results in weight loss, especially if I go easy on the grains.
I'm fine long as I'm in weight-loss mode, but one cannot stay there indefinitely. At some point, one reaches one's goal weight and must add just enough calories to maintain that weight. That's when it gets really difficult.
Here are some of the blogs I found most interesting and helpful:
Debra's Just Maintaining - This is the best blog I've found so far. There's a lot of good research here, and the author is a very good writer. She also has a healthy attitude -- she didn't hate herself when she was larger; she thought of herself as a Botticelli Babe, and judging by her photos she is attractive at both large and small sizes.
Tara Parker-Pope New York Times article -- the first part of the article is sort of depressing and hopeless, but keep reading to the end, and look at some of the blogs.
Refuse to Regain - a website about maintaning a constant weight, especially after weigh loss.
Jenny Craig - I'm put off by this company -- it's owned by a large corporation (Nestle) and charges people lots of money for frozen foods and advice. But it does seems to work for many people -- there are some good before-and-after photos and stories on the website.
South Beach Diet - I like this one. You can join for $5 per month, with no long-term contract. This is what I used to go from 165 to 145. I no longer use the South Beach diet recipes but instead look for interesting recipes on the Web or make up my own.
The Paleolithic Diet websites and blogs are interesting, but I believe they have their proportions wrong. As this Wired article points out, it's likely that most Paleolithic people ate grains and other plant-based foods at least as often as they ate meat. People such as the Inuit would have been the exceptions. Even the Inuits gather and preserve tubers, berries, grass seeds (i.e. grains), sea weed, and other vegetable material to supplement their meat and fish diets.
Paul Campos is a lawyer who makes a good case against the obsesssion with weight loss in his book The Obesity Myth. Here's a good interview in which he explains his position: http://www.theatlantic.com/business/archive/2009/07/americas-moral-panic-over-obesity/22397/
I'm editing this post to include this excellent blog: http://junkfoodscience.blogspot.com/2006/11/introduction-and-why-i-created-this.html
For years, I have traced virtually every science, food and health story in media to their original press releases, which are reported verbatim. Literally everything we hear and read today - on the internet or mainstream media - is marketing and created by those trying to sell us something: a belief, cause, product, service, or themselves. That’s why we hear “science” finds something one day, and something entirely different the next. “Pop” science, what is popularly believed and marketed as “science,” is oftentimes really the junk science.