Monthly Archives: December 2012

obesity sans overeating :(

As stated in the Laws of Energy Balance, you can get fat without eating more, and unfortunately there are about a thousand different ways to do so.  Here is yet another:

Long-term, intermittent, insulin-induced hypoglycemia produces marked obesity without hyperphagia or insulin resistance: a model for weight gain with intensive insulin therapy (McNay et al., 2012)

While it has a lot in common with fat gain diet-induced insulinemia and diabetic insulin therapy, this isn’t the greatest “model for weight gain with intensive insulin therapy.”  But it’s an interesting one nonetheless.

chocolate peppermint doughnuts

In this model, normal rats are fed the standard fare, but once weekly get jabbed  with 10 U/kg insulin; enough to drop glucose to ~35 mg/dL (seriously hypoglycemic).  Yes, this is an insulin spike, but not like the ones we normally see – usually, carbs cause the insulin spike but also provide the glucose necessary to prevent hypoglycemia.  These rats weren’t so lucky.

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Biohacking holiday weight gain

What should you eat before the big feast?  (hint: eggs.)  And don’t try to compensate in advance by eating less, this will only make you hungrier.  Furthermore, foods in your regular diet are probably healthier than holiday fare, so you definitely don’t want to eat fewer healthy foods to make room for empty calories.

Tip 1. 

Variation in the effects of three different breakfast meals on subjective satiety and subsequent intake of energy at lunch and evening meal (Fallaize et al., 2012)

Participants were served only one of these for breakfast:

And given unlimited amounts of these for lunch and dinner:

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Philosophy of the faux-low carb mouse and others like it

The Laws of Energy Balance are always maintained.  Here are some insights into how this is accomplished from a mouse perspective.  A hormonal milieu which is unfriendly for fat storage will make you lean, but not by magic.  We’ve got: 1) reduced food intake; and/or 2) increased energy expenditure.

Recall the faux-low carb mouse (Ins1+/-; Ins2-/- aka InsKO; Mehran et al., 2012).  They can’t get fat because of an inability to develop hyperinsulinemia.  Food intake isn’t reduced, so energy expenditure goes up.  Since the fat isn’t stored, it needs an “out,” so it either inhibits food intake or ramps up energy expenditure; InsKO gives us the latter.

While not hormonally-mediated, PPARg+/- mice can’t get fat because of defective adipogenesis and they handle this problem both ways; by reducing food intake and increasing energy expenditure (Kubota et al., 1999).  Similar to InsKO, PPARg+/- have lower insulin, but the primary defect in these mice is defective adipogenesis.  They can’t store fat, so this unstored fat: 1) tells the brain there’s plenty of fuel around so stop eating; and 2) ramps up energy expenditure to burn itself off:

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The faux-low carb mouse and a diatribe

The faux-low carb mouse

Hyperinsulinemia drives diet-induced obesity blah blah blah (Mehran et al., 2012)

The researchers generated a mouse with half as much insulin as normal mice.  Physiological insulin levels remain intact, but hyperinsulinemia is genetically inhibited.  For the sake of simplicity, we’ll call them “InsKO.”

When fed a high fat diet, normal mice become markedly hyperinsulinemic (pink line) whereas InsKO mice maintain relatively normal insulin levels (red line).  Blue lines are chow-fed mice; similar trend but less interesting.

divide and conquer

InsKO mice don’t get fat,

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Sir Philip Randle and the effects of blocking fat oxidation

The Randle Cycle, put forth in 1963, dictates that increased fatty acid oxidation inhibits glucose uptake and increased glucose oxidation inhibits fatty acid oxidation – it just makes sense.  Insulin enhances glucose uptake and oxidation while suppressing lipolysis; growth hormone, cortisol, and adrenaline enhance lipolysis and fatty acid oxidation which suppresses glucose oxidation.  Low carbohydrate diets reduce insulin, and the reduced glucose oxidation is metabolically irrelevant because of reduced glucose intake (by definition).  This is critical information.  And as a student of basic intermediary metabolism, I prefer the Randle Cycle over any number of alphabet soup recipes to explain metabolic phenotypes (eg, fat and carbs as opposed to IRS, Akt, Jnk, ERK, etc., etc.).  Many valuable lessons can be learned from understanding permutations of the Randle Cycle.

For example,

Inhibition of carnitine palmitoyltransferase-1 activity alleviates insulin resistance in diet-induced obese mice (Keung et al., 2012)

divide and conquer

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NRT = nicotine replacement therapy

NRT improves quitting success rates and reduces cessation-induced weight gain.  It’s a fact; and there are a lot of anti-addictive pharmacological interventions that do too.

Dear obesity researchers, primary care physicians, and smokers,
Pay attention.
Sincerely,
Bill

Rimonabant is the anti-“munchies” drug that blocks the marijuana receptor CB1.  It causes weight loss.  But 20 mg daily also increases the odds of successfully quitting smoking by 50 – 60% (Cahill and Ussher, 2007).

Relevance?
Marijuana: not really addictive.
Obesity diets: delicious, but not really addictive.
Cigarettes: definitely addictive.
Rimonabant: anti-addictive.  It causes weight loss in overweight but not lean people, perhaps because lean people don’t eat obesity diets (?).

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