Reducing insulin secretion and burning bf

[blood_drinker]

Bros, I have a question. I have understood that while insulin levels are spiked, fat loss is slowed/complicated, and NOT halted, making high carb diets less efficient at burning fat, but nevertheless, fat burning is possible .

Right?

Dan Duchaine seems to disagree. He says
"In the presence of insulin, the body will not release stored fat for energy."

MS, you yourself preach alot about my first paragraph. I have read it many times. Who is right? Do you have any studies on this? Did dan duchaine simply make a mistake? Even he himself says high carb diets work, although slower.

Someone please clarify this.

 

[Hoffmeister]

blood:

My understanding is that once released, insulin only sticks around in the blood stream for a few minutes or so, before breaking down.

So while it IS around, fat burning is stopped. But it isn't constantly there (or at least not at spiked levels; I think insulin is always present, even on keto diets, just at very low levels).

Of course, I may be totally wrong, in which case I'm sure someone will point this out

 

[blood_drinker]

MS says the opposite apparently in my theoretical misconception thread. Saying insulin levels spiked = SLOWED and not halted fat loss.

What gives, MS?

 

[dieseltwin]

Even a small amount of insulin can inhibit fat breakdown, is what the studies say.
High levels of insulin also inhibit glucagon and GH, (really good at free fatty acid release).
But then we always have some insulin, protein stimulates insulin secretion (just not as much as carbs) and even large amounts of ketones can stimulate insulin.
And then again studies also show that where the cals during excersise come from (whether from fat or carbs) doesn't determine body fat loss.
People have talked a ton about this in previous threads, but if you want a study with some numbers, here is an article you can order

http://reviews.bmn.com/medline/search/record?uid=MDLN.98018839

This study determined if the suppression of lipolysis after preexercise carbohydrate ingestion reduces fat oxidation during exercise. Six healthy, active men cycled 60 min at 44 +/- 2% peak oxygen consumption, exactly 1 h after ingesting 0.8 g/kg of glucose (Glc) or fructose (Fru) or after an overnight fast (Fast). The mean plasma insulin concentration during the 50 min before exercise was different among Fast, Fru, and Glc (8 +/- 1, 17 +/- 1, and 38 +/- 5 microU/ml, respectively; P < 0.05). After 25 min of exercise, whole body lipolysis was 6.9 +/- 0.2, 4.3 +/- 0.3, and 3.2 +/- 0.5 micromol x kg(-1) x min(-1) and fat oxidation was 6.1 +/- 0.2, 4.2 +/- 0.5, and 3.1 +/- 0.3 micromol x kg(-1) x min(-1) during Fast, Fru, and Glc, respectively (all P < 0.05). During Fast, fat oxidation was less than lipolysis (P < 0.05), whereas fat oxidation approximately equaled lipolysis during Fru and Glc. In an additional trial, the same subjects ingested glucose (0.8 g/kg) 1 h before exercise and lipolysis was simultaneously increased by infusing Intralipid and heparin throughout the resting and exercise periods (Glc+Lipid). This elevation of lipolysis during Glc+Lipid increased fat oxidation 30% above Glc (4.0 +/- 0.4 vs. 3.1 +/- 0.3 micromol x kg(-1) x min(-1); P < 0.05), confirming that lipolysis limited fat oxidation. In summary, small elevations in plasma insulin before exercise suppressed lipolysis during exercise to the point at which it equaled and appeared to limit fat oxidation.

-a

 

[MS]

The answers are all basically there. There is a danger in making absolute statements such as Duchaine's because nowhere in biological systems is there ever an all or nothing mechanism. Same with insulin. Insulin definitely inhibits lipolysis. Whether or not in inhibits nett lypolysis depends on how much insulin we're talking about, and how long the insulin stays high.

Basically insulin serves to encourage the synthesis of carbohydrate, protein AND fat.

BUT as hofmeister pointed out the effects of insulin are short term. Anyone who's suffered post-lunch dip can attest to that. Even on keto diets MOST of the fat that gets mobilized happens during rest and this is the main determinant of long term fat loss. So the best rule of thumb is to avoid carbs (especially high GI stuff) when you're not going to be doing any exercise. To rephrase that, insulin may inhibit direct burning of fat while exercising, but it does not inhibit the burning of calories which are the main determinant of fat loss success. Ultimately most of that calorie deficit coming from exercise (assuming protein intake is adequate and resistance exercise is undertaken) will come from fat stores one way or another. This is why sprinters can maintain a lean and muscular physique even though the exercise they perform is mainly glycolytic and not lipolytic. Because once they've stopped sprinting their bodies will burn fat at a greater rate for the rest of the day. Bodybuilders are really in the same boat as sprinters except that their high intensity intervals are lifting weights instead of running. There have been plenty of studies done that show that the main fat burning effect of exercise is from it's ability to maintain or increase body mass (=higher BMR) rather than it's ability to directly burn fat.