What is the role of dietary fat in weight loss?

[ociana]

I have a few questions regarding dietary fat and the part it plays in weight loss, specifically while a person is in ketosis.

First, my understanding is that dietary fat is broken down into fatty acids and glycerol through the process of catabolism. The glycerol is sent to the liver to be turned into glucose, but what is the rest of the process for the fatty acids? What process, if any, converts the fatty acid to glucose or another form of energy that can be used in generating ATP? I know that fatty acids are used throughout the body, but are they taken as ingested (post catabolism) or is there another step where they are broken down further?

Is the breakdown process for stored body fat identical to the process of breaking down dietary fat, or is there a difference? I understand that there is a difference in the "trigger" to intiate the fat breakdown process (Atkins explains that part well) but what about the process itself?

Do our bodies have a preference of whether to use body fat or dietary fat for fuel when it is currently in ketosis? In terms of calories, if you are taking in 2000 and burning 2500, will only 500 of that come from body fat or will the body prefer to use the body fat stores and discard the dietary fat?

Is there ever a time when the glycerol produced by the breakdown of fats is sent to the liver, but not converted into glucose? How does the glcerol relate to alcohol and the concept that alcohol will not get stored as fat, just burned for energy?

Almost done with these, promise.

When our bodies go into "starvation mode" due to calorie intake shortages, is the body fat the we are burning considered by the body as calorie intake? Would that go to say that starvation mode only takes place when body fat supply begins to dwindle AND you are eating a diet with decreased calories?

Now, if we are already putting our bodies into ketosis through low carbing at induction levels, while keeping our calories up at the basal caloric need (ie: just above supposed starvation mode) we will already have taken our bodies into the process of body fat burning. By starting with that step, would it not be less of a shock to the body if the calories began to decrease from that point? It would already be burning body fat as a fuel, so a gradual decrease in dietary fat would be a more natural and simple process for a body to contend with. By using that process prior to decreasing dietary fat consumption, would starvation mode even happen? Now if you are going low fat, your calorie intake will decrease anyway and you will not be already burning body fat, hence the body should take more time and stress to make the switch to body fat burning in the absense of dietary calories. That is where the Atkins advantage comes in...giving us the entry point to access the dietary fat without hitting starvation mode in the process.

So...what I am looking for here is a greater understanding of the role of dietary fat and what the impacts of reduced fat or increased fat consumption are when following an Atkins plan.

Please let me know if I need to make my questions clearer at all.

Thank You in advance!

-Oci

[ShastaHood]

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[Atkins_Nutritionist]

Here are some quick responses: If you need further clarification of this please let me know. Your questions are technical and was wondering if you have a health care background or what your specific interest was?

1. The body uses ketones for energy just as it would use glucose for energy, fats also breakdown into beta hydroxy butarate, they are not broken down further. b. They are released in the urine, breath, blood.

2. Not sure what you mean? "Is the breakdown process for stored body fat identical to the process of breaking down dietary fat, or is there a difference? I understand that there is a difference in the "trigger" to intiate the fat breakdown process (Atkins explains that part well) but what about the process itself?"

3. Our bodies use both, a preference of whether to use body fat or dietary fat for fuel depends on a persond metabolism, the amount of fat, carbs,protein one consumes, medical conditions...

4. Your example suggests a caloric deficit, so you will burn body fat stores in addition to any metabolic advantage you may get from burning on a fat metabolism over a carbohydrate metabolism

5. I am not too familiar with the metabolic pathway for alcohol. I am sure that alcohol is not metabolized using the same metabolic pathway as fat. So, I do not believe there is a relation there at all.


6. In a situation of a calorie deficit, the fat is burned because it is used to supply energy via calories. "Starvation mode" can hinder weight loss.

7. Why would you decrease calories at "that point".? ["By starting with that step, would it not be less of a shock to the body if the calories began to decrease from that point?" ] It is not healthy to eat less than our metabolic requirement of calories. People get symptoms of hair loss, dry skin... when they try to eat less calories than is necessary to maintain basic metabolic needs.

8. "By using that process prior to decreasing dietary fat consumption, would starvation mode even happen?" Yes, I explained this above.

Reducing fat is not necessary. Some people feel more comfortable in reducing fat. But, fat is impotant for hormones, brain function, inflammation, immune system....

Some people lose more weight when they increase fat.

You may want to visit www.atkins.com and immerse yourself in the thousands of research articles available. You can search specific folders based on your interest. I think you will find lots of valuable information.

So...what I am looking for here is a greater understanding of the role of dietary fat and what the impacts of reduced fat or increased fat consumption are when following an Atkins plan.

I hope this answers your questions, if not please clarify and I will try to better explain myself.

Thank you, I hope this helps.

[ociana]

First, thank you for your responses! I am not in the medical field, I just have done a lot of research into low carb eating and I am trying to fill in the blanks that exist between diet plans and the actually body processes that the food we eat goes through.

After reading your responses I attempted to find answers on the Atkins website but was unable to find the technical information I was looking for. I searched some other sites and found some helpful information, but that info left me with continued unanswered questions. Here we go...

The information I have been able to obtain about the breakdown of fats explains that they are first broken into fatty acids and glycerol, with the glycerol headed off to the liver for conversion to glucose. The fatty acids are then broken down based on this description:

Fatty acid oxidation: Like fatty acid synthesis, this is a multistep process. Each round of fatty acid oxidation produces 1 NADH, 1 FADH2 and 1 acetyl-CoA. For fatty acids to be oxidized they must be "primed" in an ATP-dependent acylation reaction to form fatty acetyl-CoA.

While that is quite technical, even for me, I get from it that in the process of breaking down fatty acids uses energy (ATP) and ends up with some byproducts, most importantly the acetyl-CoA. The acetyl-CoA then has a few options for further progress. One option is for the acetyl-CoA to enter a chemical cycle called the TCA cycle. This cycle starts with acetyl-CoA and is able to produce energy (ATP) similar to the role of glucose in the Kreb cycle. Now, the following describes another role of acetyl-CoA:

One of the fates of acetyl-CoA (in particular in instances of excess) is production of ketone bodies. This process of ketogenesis occurs mainly in the liver. The formation of the ketone bodies acetoacetate and beta-hydroxy butarate are important as they are soluble in blood, easily transported and converted to acetyl-CoA in tissues in need of energy.

Another comment I found interesting was this:

If no carbohydrate in diet, then all TCA cycle intermediates must come from protein. If acetyl-CoA is abundant from fat breakdown but not enough TCA cycle intermediates are formed from protein then acetyl-CoA goes to ketone bodies (bad breath). Since acetyl-CoA goes into ketone bodies it does not go into TCA and ATP is not generated for catabolic process. Thus this is not efficient.

The TCA cycle intermediates they mean are the other things added to the mix to get the final generation of energy (ATP). This statement, however, makes quite a bit of sense in regards to the approach of low carb eating and also the phenomenon that excess protein can inhibit weight loss (enough protein to go with the fats and you get more TCA cycles happening with more energy produced).

Another interesting tangent has to do with the breakdown of unsaturated fats:

For unsaturated fatty acids you must isomerize the unsaturation. In odd chain oxidation, propionyl-CoA is a final product. Propionyl-CoA can be converted to succinyl-CoA. Succinyl-CoA can then be converted to malate which can be transported to cytoplasm to be converted to pyruvate and then acetyl-CoA.

I take that to mean that unsaturated fats require greater energy cost to get them to the point where they can be used for energy.

Now, is that an accurate set of processes for the breakdown of fats in our bodies? Does the breakdown of body fats undergo the same process?

I still feel like my question about body fat burning counting towards calorie intake is unanswered. Here is what I am trying to figure out. A person has a basal metabolic calorie need of 1500 calories. They are actively in ketosis and their body is using body fat as part of their fuel. That person ingests 1000 calories, requiring the other 500 calories to come from body fat. Does that person's body enter "starvation mode" because they did not ingest 1500 calories or does the body recognize that the 500 calories from body fat were "consumed" also?

If our body is "consuming" body fat, then would a detrimental health impact take place with reduced calorie food intake as long as we have sufficient body fat available to meet the additional caloric need?

Atkins brings our body to the point where it is happy to use body fat for fuel, so why would it ignore that fuel source when dertermining if starvation is taking place?

Is stored body fat also able to be used for the same functions as dietary fat (brain, hormones, inflammation, immune system...)? If so, then why would a dietary fat reduction cause problems with those areas if body fat is a viable source of fat?

Thank you again for your answers and help in this!

-Oci

[Atkins_Nutritionist]

You did get good info.

I will try to explain the answers I gave you again to helpyou better understand, sorry this was not clear before, maybe I am not understanding so here is more...

Your ? about body fat is more complex than you realize. Your ? as I understand it, is not just " about body fat burning counting towards calorie intake". You must also take into account BMR (basal metabolic rate). This is a caloric factor that is important as part of the answer because your body will not go into starvation mode if you typically eat 2000 cals and decrease cals to 1600. Even though you are not into starvation mode you are burning calories. It will only go into starvation mode once you go below your BMR, in your example you say 1500 calories.

It is not healthy to go below your BMR, "starvation mode" should not be a goal. So, the body goes into "starvation" because you are not getting the calories you need.

It is a myth that when doing Atkins your body goes into starvation. The goal is always to eat enough to prevent "starvation". The reason there is confusion is because ketosis occurs in people who are starving. You can also get into ketosis by reducing your calories to low levels, again this is not healthy. On Atkins, you "trick" your body into thinking it is starving by decreasing the carbs so it burns fat instead of having to starve yourself and your body still gets the calories it needs because you should only be shifting the nutrient composition , ie on 1500 cals from 55% carbs to 5-8%. (let me know if this point is clear)

The example you give, "A person has a basal metabolic calorie need of 1500 calories. They are actively in ketosis and their body is using body fat as part of their fuel. That person ingests 1000 calories, requiring the other 500 calories to come from body fat. " Yes, the person is burning fat stores but I am not sure that this is the healthiest way to lose weight because you are not getting the nutrients you need. If you are overweight, you are likely eating 2000 cals so if you eat enough for your BMR, 1500 cals, you will lose weight safely and effectively without having to jeopardize your health.

"Does that person's body enter "starvation mode" because they did not ingest 1500 calories" ---yes.

"or does the body recognize that the 500 calories from body fat were "consumed" also?" --yes it is recognized as a source of fuel just as the food you eat is recognized as fuel.

If our body is "consuming" body fat, then would a detrimental health impact take place with reduced calorie food intake as long as we have sufficient body fat available to meet the additional caloric need? No, but if your calories go below the amount your body needs,"starvation mode", YES.

"Starvation mode" is an involuntary reflex. Atkins brings our body to the point where it is happy to use body fat for fuel, so why would it ignore that fuel source when dertermining if starvation is taking place?

"Is stored body fat also able to be used for the same functions as dietary fat (brain, hormones, inflammation, immune system...)?" Yes

If so, then why would a dietary fat reduction cause problems with those areas if body fat is a viable source of fat? Just because you eat less fat it does not mean you will burn more fat. This goes against the whole Atkins principle (see why Atkins or how atkins work-specifically search the "atkins principles") and starts to shift towards the low fat theory. Also if you go to the site, go to the Science behind atkins section, look in the folder "research supporting Atkins". In this folder there are studies (ie by Greene and others) that show:

1. when consuming equal calories (1500 cals), the body loses more weight when the nutrients are most similiar to Atkins (23 pounds and 5%carbs,65% fat vs.17 pounds on 55%carb, 30%fat).
2. consuming 300 calories more (1800 cals) induced a greater weight loss than those following low fat (1500 cals)

This occured as a calorie deficit not due to eating less than a persons individual BMR and being in "starvation mode".

[ociana]

Thanks for the response...I am going to start a new thread with my questions that have come up regarding starvation mode...

-Oci