Copyright © 2009
by Daniel Matthew Korn

All Rights Reserved

Weight gain is usually thought of as a single process, yet when we look closely at extremely obese people we can see two general problems. The first one we have already discussed in detail, a high level of hunger. In 2007, 29-year-old Renee Williams became the largest person ever to have gastric bypass surgery. She weighed close to 1,000 pounds before her surgery, leading MailOnline to refer to her as the “half ton mum.” In reference to her own appetite she said, “When you don't have that thing in your head that tells you you're full, it's disgusting the amount of food you can eat.” One of her daughters said, “She would get about eight burgers and eat them all. I kept telling her she was eating her emotions.”¹

Renee’s story illustrates the aspect of weight gain with which we are most familiar, increased appetite. Appetite and weight gain are the attributes of obesity that have received the most attention and research because they are its most visible features. What Renee described as not having the thing in her head to tell her she was full is called insulin resistance. It is associated with high levels of cortisol, high blood pressure, and weight gain.² However, there is another characteristic of obesity which is just as important but about which we know less. This relates to the body’s ability to use stored fat.

Without hunger and with perfect access to stored fat, we could lose weight quickly and easily. With excess hunger, we gain weight. There is another factor in addition to hunger which can affect weight: the ability of the body to use stored fat. The body cannot directly use fat in the form stored in fat cells; to convert this fat to a usable form it has to undergo a process called fatty acid degradation. The final stage of this process releases usable energy and is called fat oxidation, or fatty acid oxidation.^3,4

People who are obese tend to have a decreased ability to use their stored fat. In medical terminology, they have lower rates of fat oxidation; in other words, they use less stored fat for energy. Among wild animals, whose diet has not changed the way that of humans has, we see a much greater ability to use stored fat than what humans are currently experiencing. Bears hibernate for roughly seven months while getting all of their energy from stored fat. Ruby-throated hummingbirds fly nonstop for approximately 1,500 miles with only their stored fat for energy.⁵ These feats are possible because of these animals’ great ability to use stored fat.

After a person with a low rate of fat oxidation has used all of the energy from his most recent meal, he becomes hungry and eats more rather than getting energy from his stored fat. However, in the presence of sufficient body fat, low blood sugar is supposed to be a trigger for a process in which stored fats are used for energy. Experiencing hunger when blood sugar drops, such as between meals or at night, implies a lowered ability to use stored fat. When meals are adequate, hunger between meals is biological rather than psychological, as we can see from the experiences of extraordinarily obese people who have gone on diets containing very limited calories.

Gastric bypass surgery is one extreme example of an attempt to deal with obesity. Going on a very low calorie diet is another. Michael Edelman was listed by the Guinness Book of World Records as weighing 994 pounds; his mother estimated that at his heaviest he weighed 1,200 pounds. He stopped going to school at age ten because he could not fit into his desk. He tried every new diet that came out, yet nothing worked for him. After the death of a friend due to obesity, he developed a fear of eating and would eat only when spoon fed. He quickly lost hundreds of pounds, yet starved to death while weighing roughly six hundred pounds.⁶

Starvation is supposed to occur after the last remnant of fat has been used.⁷ Pictures of starving people in Ethiopia show bodies with almost no fat. However, in the low calorie diet experiments we saw earlier, very overweight people exhibited symptoms of starvation when they still had large amounts of body fat. In addition to the example of Michael Edelman, other obesity sufferers have died of starvation on low calorie diets, despite still being severely overweight. Dieters on low calorie diets often lose muscle instead of fat. This implies that in addition to increased hunger, a reduced ability to use stored fat is present in obesity.

Research has linked lower levels of fat oxidation to higher body weight,⁸ and high body weight to stress and sleep deprivation. In at least one study, higher levels of fat oxidation corresponded to lower levels of hunger.⁹ Some followers of different diets have reported that their hunger becomes less intense. Rather than feeling an urgent need to eat or an intense craving, they feel as though they have forgotten to eat, but the sensation is not urgent.

The effect is not something that has been consistently reported on a single diet or by all followers of a certain diet, nor is it something that has been scientifically investigated. Scientists have done studies measuring the quantity of hunger,¹⁰ but there is no way to measure a different type of hunger. The cause is probably not related to the main points which diets recommend. Otherwise all of a particular diet’s followers would be experiencing what has been referred to as “appetite suppression” or “a lower degree” of hunger. If a different quality of hunger does exist, it is something that we are stumbling onto accidentally without an adequate explanation. However, impaired fat metabolism is measurable and its ability to hinder weight loss and possibly increase hunger is very real. As we will see, there is some overlap between the causes of increased hunger and impaired fat metabolism.

  Last Chapter       Next Chapter 

Citations:

² "Insulin Resistance." Wikipedia. 6/04/2009 http://en.wikipedia.org/wiki/Insulin_resistance.

³ A.M. Poynten and others. "Fat Oxidation, Body Composition and Insulin Sensitivity in Diabetic and Normoglycaemic Obese Adults 5 Years After Weight Loss." International Journal of Obesity. 6/04/2009 http://www.nature.com/ijo/journal/v27/n10/full/0802393a.html.

⁴ "Fatty Acid Degradation." Wikipedia. 4/04/2009 http://en.wikipedia.org/wiki/Fatty_acid_degradation.

⁵ Idem.

⁶ "The World's Heaviest People." Dimensions Magazine. 6/04/2009 http://www.dimensionsmagazine.com/dimtext/kjn/people/heaviest.htm.

⁷ Michael W. King. "Fatty Acid Oxidation." The Medical Biochemistry Page. 6/04/2009 http://themedicalbiochemistrypage.org/fatty-acid-oxidation.html.

⁸ A.M. Poynten and others. "Fat Oxidation, Body Composition and Insulin Sensitivity in Diabetic and Normoglycaemic Obese Adults 5 Years After Weight Loss." International Journal of Obesity. 6/04/2009 http://www.nature.com/ijo/journal/v27/n10/full/0802393a.html.

⁹ Emma J. Stevenson and others. "Fat Oxidation During Exercise and Satiety During Recovery Are Increased Following a Low-Glycemic Index Breakfast in Sedentary Women." Journal of Nutrition. 6/04/2009 http://jn.nutrition.org/cgi/content/abstract/jn.108.101956v1.

¹⁰ T. A. Wadden and others. “Less Food, Less Hunger: Reports of Appetite and Symptoms in a Controlled Study of a Protein-Sparing Modified Fast.“ International Journal of Obesity, (1987) Vol. 11, No. 3, pp. 239-49. Journal code: 7703240. ISSN: 0307-0565.