What Everybody Knows About Being Fat
But everybody knows that people get fat because they eat too much!
The NIH in 1992 stated that the underlying causes of obesity were largely unknown, however obesity research has since uncovered several factors which likely cause or contribute to obesity. The bottom line appears to be a certain set of genetics combined with a society which calls for very little labor and offers very rich tasty food at every corner. A certain number of individuals who get very large appear to have a damaged hypothalmus - this causes them to constantly feel hungry, even after consuming a large meal. The feeling of hunger with an intensity which makes it close to painful is felt constantly by these individuals so they often end up stretching their stomachs to be able to consume a large amount of food at a sitting (which they do often during the day) and combining that with inactivity, part of which comes from the difficulty of moving around at their size, they can become very large, some weighing 1000 lbs or more. There is no known cure for a damaged hypothalmus. Unfortunately, even those individuals getting weight loss surgery may not lose the niggling, painful and constant feeling of hunger they have. (The hypothalmus can also have an effect on body temperature - running a degree lower than 98.8 can greatly lower the metabolism).
The medical community and general public hold the strongly entrenched belief that most obesities are caused by an excessive amount of caloric intake with low energy expenditure. Most treatment models assume the obese eat considerably more than the non-obese and that daily food intake must be restricted in order to ensure weight loss.
This belief is directly opposed by Stunkard, Cool, Lindquist, and Meyers (1980), and Garner and Wooley (1991) who contend that most obese people do NOT eat more than the general population. There is often no difference in the amount of food consumed, speed of eating, bite size or total calories consumed between obese people and the general population. ["Methods for voluntary weight loss and control", Technological Assessment Conference Statement; 1992 Mar 30-Apr 1. Bethesda (MD): National Institutes of Health, Office of Medical Applications of Research; ; Stunkard, A., Coll, M., Lindquist, L., & Meyers, A. (1980). "Obesity and eating style", Archives Of General Psychiatry, (37), 1127-29; Garner, D., & Wooley, S. (1991). "Confronting the failure of behavioral and dietary treatments for obesity", Clinical Psychology Review, (11). 729-80; Rhonda Zabrodski BSc, MSW, RSW (thesis)].
Leptin theory relates to issues of metabolism. If one's metabolic rate is reduced to ensure survival [when dieting], fewer calories are needed. More leptin is manufactured telling the fat cells to store more fat and also increasing the appetite. This is a natural bodily mechanism to insure that when the thought-to-be starving person is in the presence of food, s/he will eat. The longer the diet lasts, the more leptin in the blood creating that ravenous appetite that people often experience after a prolonged diet. The body also reduces the caloric needs of the individual during a diet by consuming its own muscle tissue and replacing it with fat which doesn't burn any calories (1 lbs of fat burns 2 calories a day, 1 lb of muscle can burn 50 calories a day). This is why when people are dieting, they lose much more muscle than fat. Also, the body can only get simple carbohydrates out of fat and must leech its protein from muscles and organ tissue. Conservative estimates say that on a diet, only 30 percent of the weight you lose is fat! The Leptin studies were done on rats and when humans were tested, appetite appeared to be much more complex than in rats. Oh well.
In 1994, Scientists in Canada noticed a strange thing. Observing dieting individuals they noticed that the general tendency in dieting individuals was that they appear to gain more weight on fewer calories, when the diet stops. This phenomena is often found in women who have endured a very low calorie liquid protein diet (VLCD) that consists of 500 calories per day. Weight is lost initially, stabilizes and when calories are increased to just 800 per day, weight is GAINED. The Canadian scientists attributed this phenomena to a lowered set point but modern research tends to attritute this phenomena to leptin levels, consumption of muscle tissue and other. [(College of Physicians and Surgeons of Alberta. (1994). Very low calorie diets. (policy paper); Rhonda Zabrodski BSc, MSW, RSW (thesis)].
Also observed about setpoint is that in normal people, the setpoint stays at close to ideal weight (which is a lot heavier than BMI grading suggests) or goes down. But in fat people, the set point can go up also if they gain to a new high. And even when they diet, their bodies don't lower the set point as do the bodies of normal individuals. A study had two groups gain weight. One group was normal sized individuals, the other was composed of obese individuals. They all gained at least 20 lbs and after six months were told to lose the weight. The normal sized individuals were back to their normal weight within weeks without much work. The obese individuals had a very hard time losing the weight. Scientists theorized that the set points of the obese individuals had been raised during the weight gain and now their bodies were fighting to maintain the higher weight. (Pool)
Obesity is mostly genetic, scientists have observed. Twin studies have shown that twins separated at birth and brought up in very different environments tended to be about the same weight all during their childhood and even into their adulthood.. [A.J.Stunkard, J.R.Harris, N.L.Pederson & G.E.McClearn, "The body-mass index of twins who have been reared apart", New England Journal of Medicine, vol. 322, 1483--1487; Rhonda Zabrodski BSc, MSW, RSW (thesis)].
Scientists have isolated at least two genes which may cause obesity. One is the "diabetic gene" (which also causes diabetes in most individuals who carry this gene, whether fat or thin) and the "thrifty gene", a gene found in communities like the Pima Indians - this gene causes the body to burn fuel extremely conservatively and also causes people to have a big appetite when they are in the presence of food. (Pool) Dr Rudy Liebel stated that there may be as many as 40 genes involved.
Many fat people who don't diet, normalize their eating habits found Janet Polivy, who continued to do studies on restrained eating. Eventually, they would show that fat people who didn't diet ate just like normal people. [J. Polivy and C. Peter Merman, "Dieting and Bingeing: A Causal Analysis", American Psychologist, vol. 40 (1985); Fraser, L., Losing It: America's Obsession with Weight and the Industry that Feeds on it, 1997, Dutton (New York), P. 242.]
K. S. Kissileff and others at the University of Pennsylvania found that fat and thin people ate under similar circumstances... The investigators found that fat and lean people differed in none of their eating habits. [K.S.Kisseleff, H.A. Jordan & L.S.Levitz, "Eating Habits of Obese and Normal Weight Humans", International Journal of Obesity 2, 1978, p. 379; W. Bennett, MD & J. Gurin, The Dieter's Dilemma, 1982, Basic Books, Inc. (New York), P. 55.]
The following books have information on Obesity research
More information about the long term studies of 20,000 men (showing that fat and fit men live much longer than thin and unfit men) can be found at (The Cooper Institute):
More on size acceptance