Why Fat Doesnt Make You Fat..

[badly_dubbed]

[MJ.23]

I stopped reading after,

"Carbs are killing you."

I am very pro fat; but people need to stop alienating macronutrients.

[badly_dubbed]

i agree, i meant it in lightheartedness - of course carbs wont kill you....

its just a less techy way of showing a process

[chill9]

This is brilliant, I hate the whole low fat marketing ********. The NHS don't do enough to explain this to the overweight nation. This poster explains it in laymans terms for them! Of course if only they would get of their fat arses and do some exercise that would help too!

[hailtotheking]

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i agree, i meant it in lightheartedness - of course carbs wont kill you....

its just a less techy way of showing a process

... a process that is only a half-truth baked up by a bunch of narrow-minded dogmatic zealots, conveniently ignoring a whole host of other factors that dont sit happy with low carbers like the overriding effect of energy balance, water balance, effects of glycogen repletion / depletion, failiure to show improvement over other diets when calorically matched in the long term, etc. and for many other problems like deteriorated mood, mental function, physical performance, blood profile, high blood glucose,impaired insulin sensitivity, etc.

[NU_nutrition_TS]

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...the overriding effect of energy balance, water balance, effects of glycogen repletion / depletion, etc.

Overriding? Interesting interpretation - but one that I do not share.

While obviously simplified for the masses, the chart does more or less accurately reflect (based on decades of scientific research) the overriding factors that control fat storage or release and, therefore, how much fat tissue we accumulate or lose over the longer term.

The other factors you say are overriding are, in my opinion, incidental to the basic mechanism.

If how many extra calories (on top of maintenance requirements) was an overriding factor in the mechanism of body fat accumulation, you would have to explain how a unit of potential energy value (in and of itself) directly controls partitioning of those units of energy in terms of foods eaten, while by-passing or overriding the partitioning action of insulin.

As the science currently indicates and as reflected in the chart, insulin is secreted in proportion to the type of food being eaten, with carbohydrates being associated with the greatest insulin release followed by some proteins with fats eliciting hardly any release.

Fats have more calories than either carbohydrates or proteins so, if calories were an overriding factor, one would expect to logically see the inverse association between macronutrient content and insulin response as is actually the case.

You would also have to explain why there is no predictable, linear relationship between calories ingested (or not) and fat accrued (or not) or lost (or not) - even in subjects who serve as their own controls - while there are studies showing a relationship between levels of insulin sensitivity, and basal/postprandial secretion of insulin, and future fat mass gain.

[NU_nutrition_TS]

I've been racking my brain trying to think of a simpler, clearer way to make the point without coming across as a 'narrow-minded dogmatic zealot'!

Let's try this tack - just taking 'caloric balance' as an example.

We have two competing hypotheses (perhaps complimentary may prove to be more accurate?): a) eating more calories - irrespective of their source - than one expends is the driving factor in fat gain or b) eating a high proportion of calories as easily digested carbohydrates is the driving factor in fat gain via their stimulating effect on insulin secretion.

Now, where research has shown significant success in fat loss for low carbohydrate diets, the counter-claim is usually that people who adopt such a diet spontaneously reduce caloric intake and that is the reason for the fat loss.

It is not disputed that, in a great many cases, caloric intake is spontaneously reduced on a low carbohydrate diet. It must also be acknowledged that caloric reduction is often not intentionally enacted by researchers or subjects and that such unconscious, spontaneous reductions in caloric intake are usually not accompanied by sensations of hunger or deprivation. The latter condition would appear to be necessary for the former to occur.

On the other hand, if the macronutrient content of a diet is not changed but total calories are deliberately reduced, the subject will often report increased hunger and deprivation. The fact that lack of will power (poor compliance) is often blamed for a failure to succeed on calorie-reduced diets can be taken as evidence for this increased hunger.

So what is the major difference between the two approaches? It is not calories, per se, as often those individuals who spontaneously reduce their caloric intake on a low carbohydrate diet often match the intake of those individuals who deliberately reduce their intake without changing the macronutrient profile of the diet. Therefore the obvious difference between the two is the macronutrient profile.

Having established the above, the question becomes by what mechanism does the altered macronutrient profile of the diet effect the change in the experience of the subject if not the physiological endpoint (fat loss) to any statistically significant degree?

Clearly this must have something to do with how certain macronutrients impact on metabolic factors.

Hunger, while registered in the brain and resulting from a complex biochemical signalling process, has a physiological root stimulus: a lack of available energy to the cells. If you have reduced your caloric intake, it stands to reason there is less energy available to cells. The idea being, that if you have excessive energy storage in the form of fat, this should be liberated to feed the cells. If this occurs, cells don't go without the necessary energy substrate and you should not feel excessive hunger or deprivation. This is obviously the case in those who eat the low carbohydrate diet and spontaneously/unconsciously reduce calories but not so much in the person who consciously follows a calorie-restricted diet without manipulation of macronutrients. Why?

As the poster explains - among many of its roles - insulin controls how much fat is stored or released from adipocytes. Dietary carbohydrates tend to have the greatest impact on insulin release. The greater the level of insulin, the less easily fatty acids can be released from adipocytes. If the cells are not receiving the energy they require from food directly (on a calorie-restricted diet) or from stored fatty acids (because adipocytes won't release them) then those cells have to signal the brain to increase hunger.

So one can see how the macronutrients, more so than the calories, influence the ability to mobilise fat from storage. I would therefore conclude that caloric balance does not override the hormonal signalling that controls fat storage and release via the effect certain macronutrient profiles have on insulin secretion.

As an addendum: Why do calorie-restricted diets that do not alter macronutrient ratios from the basic P20:C50:F30 pattern work at all? As explained above, if the person using such a dietary approach can muster the will-power required to endure the feelings of increased hunger and deprivation, the body will eventually respond to that caloric deprivation by making changes at the metabolic and hormonal levels to allow progressively more fat to be released from the adipocytes. Also, if you drastically cut calories and keep macronutrient ratios the same, you are ipso facto reducing carbohydrate but not to a low enough level where metabolic adaptations to improved fat release and oxidation can progress rapidly.

[badly_dubbed]

on the last paragraph there NU, for anyone who is a little confused

lowering insulin should make a person bear going without food for longer due to the mobilisation of stored body fat?

so at which point (even when there is still stored body fat present) do the cells 1) stop receiving energy directly from foood and 2) stop receiving energy from stored fatty acids therfore creating hunger?

[NU_nutrition_TS]

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Lowering insulin should make a person bear going without food for longer due to the mobilisation of stored body fat?

I would put it this way:

Mobilisation of stored body fat for use as an energy substrate for cellular function is likely to reduce hunger when cutting back on food intakes. Keeping insulin levels low will greatly facilitate release of stored fatty acids (lipolysis). Reduced hunger will, in turn, mean less food has to be eaten or eaten less frequently (go longer between meals)

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So at which point (even when there is still stored body fat present) do the cells 1) stop receiving energy directly from foood and 2) stop receiving energy from stored fatty acids therefore creating hunger?

Cells would only stop receiving energy directly from food if you stopped eating altogether. When cells get energy from stores (fat, glycogen) you could say that they are receiving their energy from food indirectly because those stores are made up of excess substrates from previous meals. The cells would stop receiving energy substrates from storage when those stores were exhausted (death by starvation). Or when those stores are prevented from releasing their contents or the cells are prevented from taking them up. In most cases, when the body is working properly and at a healthy composition, energy should be supplied by a combination of both food immediately digested and storage release. Hunger (and thus food intake), at this point, should match the body's energy requirements.

[chill9]

So to burn fat we would have to burn off the food immediatley digested first?

Or all the glucose available to us our blood stream and glycogen stored in our muscles at the time?