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Obesity, Leptin Resistance, and Dietary Fructose

Michael's picture

Why is there so much focus on dietary fructose these days? Why is it thought to be a 'bad' carbohydrate?

I found some answers while I watched an interesting lecture—Obesity: The Plague of the 21st Century—on the Research Channel.

The lecture was about body fat regulation mechanisms and how they contribute to obesity. Research indicates that the hormone Leptin is involved in body fat regulation, and that the body's fat stores can alter Leptin levels—which creates a perverse feedback loop in which body fat may act to raise your 'normal' weight set point, thus frustrating long-term efforts to reduce weight and keep it off. Researchers found that injecting Leptin into obese patients results in a dramatic return to 'normal' body fat levels.

Other interesting points mentioned:

  • Body fat is regulated by the body.
  • Studies show that low-fat, reduced calorie diets are effective for weight loss (at least for the duration of the studies); reduced carbohydrate, high-protein, low fat diets are even more effective.
  • The Minnesota Starvation Experiment conducted during WWII demonstrated strongly negative physiological and psychological effects of severe caloric restriction: reduced metabolism and obsession with food to name but a few. Starvation dieters beware!

After watching the lecture, I began reading more about Leptin, and in doing so, found that Leptin resistance is associated with obesity, and that there is some evidence to suggest that diets high in fructose can set you up for serious weight problems by increasing your body's resistance to Leptin.

This is fascinating. It seems that the abundant availability of and easy access to fructose-laden processed foods combined with decreased physical activity are the likely culprits in the current obesity epidemic. This is no revelation, but it is interesting to me that prosperity and the economics of convenience may be our own worst enemies in fighting long-term health problems created by obesity.

(You can find more information regarding fructose or Leptin in the archives.)

Another interesting read: What Do We Know About Fructose And Obesity?

Update 3/14/2010
How safe is fructose for persons with or without diabetes? (An American Journal of Clinical Nutrition editorial describing the ways in which fructose does its damage.)

Fructose is a simple sugar found in honey, fruit, table sugar (sucrose), and high-fructose corn syrup (HFCS). Because of the worldwide increase in the consumption of these sweeteners, fructose intake has quadrupled since the early 1900s (2). The past 30 y have witnessed an even greater acceleration in consumption, in part because of the introduction of HFCS; this phenomenon parallels the rise in obesity, diabetes, hypertension, and kidney disease (2, 3). Whereas associations do not prove cause-and-effect, experimental studies in animals have shown that fructose can induce most features of the metabolic syndrome, including insulin resistance, elevated triglycerides, abdominal obesity, elevated blood pressure, inflammation, oxidative stress, endothelial dysfunction, microvascular disease, hyperuricemia, glomerular hypertension and renal injury, and fatty liver. These effects are not seen in animals pair-fed glucose or starch, which suggests that the mechanism is not mediated by excessive caloric intake (4). The consumption of large amounts of dietary fructose also can rapidly induce insulin resistance, postprandial hypertriglyceridemia, and blood pressure in humans more than starch (or glucose) does in controls (3, 5, 6). Moreover, it is a potential risk factor for fatty liver disease (7). (Emphasis mine)

Update 3/27/2010
The HFCS debate heats up: Latest high-fructose corn syrup study generates buzz, debate

(CNN) -- Acolytes of "Food Rules" guru Michael Pollan and other well-meaning foodies who've made corn a scapegoat for the nation's health crises have welcomed a new study from Princeton University that suggests high-fructose corn syrup causes more significant weight gain than table sugar.
But the findings have been criticized by food science experts and industry veterans, who say the study unfairly demonizes corn syrup and implicitly absolves cane sugar of responsibility for making Americans fat.

Counterpoint: Skepticism Grows About High Fructose Corn Syrup Hype

Every day, more people are pointing out flaws in last month’s Princeton University study finding that rats fed high fructose corn syrup gained more weight than rats fed sucrose (table sugar). The authors of the research speculated that this could signify that high fructose corn syrup has a unique role in fueling America’s “obesity epidemic.” Earlier in the week, however, nutrition professor Marion Nestle detailed her confusion about how the researchers could have reached that conclusion. Today Washington Post health writer Jennifer LaRue Huget voices her skepticism with the Princeton study, writing that the evidence is “not convincing enough” to support the authors’ speculations.

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About Michael

Michael's picture

About me

I'm Mike. I'm LowCarbForLife's (Teri's) hubby. I manage the LowCarbCompatible™ web site, among many other things. I don't follow a strict diet but I do follow LowCarbForLife's way of eating most of the time, since we eat together (and I cook most of the time).

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Current Diet Type
Carbohydrate Addict's Lifespan Program (CALP)

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