I recently watched two speeches given by Dr Robert Lustig on the role fructose (may?) plays in the on-going obesity epidemic (link, link). IMHO, it's pretty conclusive and does seems to explains some of the paradoxes (see this Gary Taubes talk @ Google) seen with the calories balance dogma.
Here's are the notes I took from the videos:
- Observations
- Atkins and Japanese [Okinawa diet?] diets both eliminate fructose
- All countries which have adopted a USA style diet have the same obesity issue
- The First Law of Thermodynamics in nutrition is stated in an incorrect way: "if you eat it, you must use it or you are going to store it". It should be "if you store it and you expect to burn it, you going to have to eat it"
- An epidemic of obese 6 months-old means that any attempt to explaining the overall issue, but also explain this. It's not all about diet and exercise
- We are all eating more than before, there is something wrong with our bio-chemical negative system which control our eating:
- +187 kcal/day for men
- +335 kcal/day for women
- +275 kcal/day for teens
- We are not eating more fat, we are eating more carbs as soft drinks and fruit drinks (1 soda can per day = 15.6 lbs per year of weight gain)
- How come leptin doesn't work to regulate our energy intake?
- What happened?
- Soft drinks consumption is demonstrably (studies) linked to obesity and diabetes (type 2)
- Soft drinks are loaded with High Fructose Corn Syrup (HFCS) which is sweeter and cheaper than Sucrose (one molecule of Glucose for a molecule of Fructose).
- Fructose and Glucose are NOT the same, however Sucrose and HFCS are the "same": they are both poison. It's not about the calories.
- Excessive consumption of any sugar does lead to health problems
- Trend in fructose consumption (*2 for sucrose):
- pre-WWII (natural) consumption (fruits & veggies): 15 g/day
- 1977 consumption: 37 g/day
- 1994 consumption: 54.7 g/day
- Today teen consumption: 72.8 g/day
- Today consumption per person: 140 lbs/year
- The "Perfect Storm"
- Drive to make food cheaper (1972)
- Invention of HFCS (1966) which is now in pretty much every processed food
- Call for dietary fat reduction (1982) to reduce heart disease: dietary fat raise LDL -> LDL correlate with cadio vascular disease (CVD) so dietary fat must lead to CVD
- 30 years of nutrition guidelines has been based on a faulty study (The Seven country)
- To make low-fat food palatable, carbs (either HFC or sucrose) were substituted to fat. Fibre and trans fat were also removed (for a longer shelf life of the products)
- Sugar hides:
- salty (chew mix, honey roasted peanuts ...)
- sour (German wines, Lemonade ...)
- umami (sweet & sour pork ...)
- bitter (milk chocolate ...)
- What is the issue?
- Fructose is NOT Glucose
- Fructose (which is very sweet) is 7 times more likely than Glucose (which is not very sweet) to form Advanced Glycation end-products
- Fructose makes you eat more:
- Hepatic fructose metabolism is different from glucose's
- Chronic fructose exposure promotes the Metabolic Syndrome
- How the liver deal with:
- 120 kcal of glucose (2 slices of white bread, 1/4 cup of white rice)
- 80% of it will be used by the body as all cells use glucose as glycogen
- 20% of it will be metabolised, resulting in 1 kcal of VLDL and insulin release which will stop the eating
- 120 kcal of ethanol (which is fermented sugar)
- 20% of it is absorbed by the intestine
- 80% is metabolized resulting in VLDL (no glycogen)
- 120 kcal of sucrose (1 glass of Orange Juice)
- 30% of the fructose end-up as fat (no glycogen)
- metabolising will lead to:
- habituation, if not addiction
- fetus insulin resistance
- hypertension
- myocardial infarction
- dyslipidemia
- pancreatitis
- obsesity
- hepatic dysfunction
- What can be done?
- Lifestyle intervention
- get ride of all sugared liquids
- eat your carbs with fibre
- wait 20 minutes for second portion
- increased physical activities
- Why is exercise important to obesity (since exercising doesn't burn enough calories)?
- improve skeletal muscle insulin sensitivity
- reduce stress and resultant cortisol release
- makes TCA cycle run faster and detoxifies fructose, improving hepatic insulin sensitivity
- Why is fibre important in obesity?
- where-ever there is fructose in nature, there is more fibre (fruits are okay to eat; only grapes have more sugar than fibre)
- reduces rate of intestinal carbs absorption, reducing insulin response
- increases speed of intestinal transit (or contents to ileum)
- induces satiety
- inhibits absorption of some free fatty acids to the colon; which suppress insulin
- Why is the government not doing anything?
- Summary
- Fructose (in sucrose or HFCS) consumption has increased over the past 30 years, coinciding with obesity epidemic
- A calorie is not a calorie and fructose is not glucose
- You are not what you eat; you are what you do with what you eat
- hepatic fructose metabolism leads to all the manifestation of the metabolic syndrome
- fructose ingestion interferes with obesity intervention
- fructose is a chronic hepatotoxin ("alcohol without the buzz")
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