Sunday, 20 December 2009

Limit fat when losing weight

So I have been losing weight the Paleo way. A further 1kg over the last 2 weeks. This is net loss, as muscles seem to be getting bigger and waistline smaller. It is likely that following this regime about 100g of fat is burnt each day.

When trying to figure out how much dietary fat I would need IF I were not losing weight, just to maintain it, I estimated this to be about 100g. So, since I am getting the fat from my adipose tissue, perhaps I should not eat it?

Let us have a look at the fat being burnt while losing weight: the human suet (or lard). Is it good fat or bad fat? Well, on average it is mostly monounsaturated (57.5%) and saturated (26%). It is, however, high on PUFA (14.4%) with omega-6 13.6% and omega-3 only 0.78%:
http://www.ajcn.org/cgi/content/abstract/42/6/1206
Interestingly, this depends on human diet, so high PUFA in the diet translates to high PUFA in adipose tissue. Most likely people losing weight have higher PUFA content in their fat, even those on low fat diet. Very low fat diet would mean more endogenous synthesis from glucose and fructose, and possibly less PUFA in fat.

Incidentally, losing weight also means "eating" some cholesterol. Burning 100g of your own fat releases about 400mg of cholesterol, roughly equivalent to two eggs a day.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC301844/
This is something to be aware if your concern is that you might be getting too little, rather than too much of it.

The bottom line is: when losing weight limit consumption of total fat, but also make sure you are getting omega-3 to balance the omega-6 released from the adipose tissue. This might mean quite a lot of omega-3, possibly 10g, which can be hard to achieve by just eating fish.

Does it mean that when burning fat we should only be eating almost exclusively meat and fish along with low carb leafy veggies? This is likely to be the case, but I have not seen any recommendations specific to continuous weight loss.

I have about 5kg more fat to lose. After that I am going to indulge in fat.

6 comments:

  1. Interesting point. I'm still trying to figure out why some of the fitness folks are advocating so much omega 3 (.5/1g per 10lbs body weight), but it certainly seems prudent to compensate for burning stored body fat.

    BTW, I think you mean omega 3 in this sentence, don't you? It's from the third to last paragraph.

    "This might mean quite a lot of omega-6, possibly 10g, which can be hard to achieve by just eating fish."

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  2. One other comment. I suppose it depends on what meat and fish you're eating, but I think one of the benefits from a paleo/primal approach is the satiety from eating fat (not to mention the advantage for absorption of some of the nutrients in your food).

    Obviously you need to have a net calorie loss, so eating too much fat is counter-productive. But I'd bet that eating too little would be as well.

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  3. Beth,
    Many thanks for yor comment and for spotting the typo.

    I believe that often omega-3 is often promoted to push supplements. As Stephan from Whole Health Source suggests, it might be better to lower omega-6 than to increase omega-3. And both of them combined are an issue as fats most susceptible to oxidation.

    Now that I think about it, I am not at all sure that going high on omega-3 in weight loss mode is better even if that helps reduce inflammation. Is inflammation worse than oxidation? Or perhaps the optimal strategy would be to increase intake of omega-3 but also eat loads of fresh leafy vegetables, maybe even supplementing short term with vit E?

    Also exercise during weight loss phase is critical: more aerobic training would mean more lipid oxidation, another reason to focus on resistance + long walks while losing weight.

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  4. Interesting post! Just so I'm understanding, are you saying that you're pro-fat, just not during attempts at weight loss? (I'm new to this blog and came upon this post from a google search)

    This post has me thinking. Allow me to talk out loud as I ponder some thoughts.

    It's so hard for me to get enough calories -- even while consuming a large amount of fat ever day -- that I can't imagine someone being able to do a low fat paleo diet without necessarily adopting a severely hypocaloric diet.

    Or perhaps this wouldn't matter since you would be liberating enough fat in your body that this makes up for the calories you are not consuming?

    My mother-in-law is trying to lose weight on a low-carb/paleo diet, but isn't having too much success. Her fat intake is about 70% of her daily calories (followed by protein and then vegetable carbs). What you're saying is that it would actually be better to limit the fat, eat lean protein sources, and fill up on vegetables?

    I remember back in the early 2000s when I read Atkins' book for the first time. I think he said that you have to eat fat to burn fat, and if you tried a low fat version of his diet that it wouldn't work. I'm not an Atkins fanatic, but I do wonder why he would come to that conclusion.

    On a related note, I know there is some talk about palmitic acid causing temporary insulin resistance. Stephan has written about it on Whole Health Source. While this is a temporary and reversible state, I do wonder if it has a negative effect if the goal is weight loss. Would it not be better to temporarily limit sources of palmitic acid and avoid any windows of insulin resistance altogether?

    If you have any thoughts on my thoughts, I'd love to hear them. Again, very interesting post. I'll have to check out the rest of your blog!

    David

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  5. Hi David, many thanks for your comment. Indeed, I feel that limiting fat during the weight loss period is recommended. Perhaps fat should be increased gradually (or stepwise?) as the waistline gets thinner. I believe Art De Vany recommends limiting fat, but do not know what his advise on weight loss would be.

    Also, think about your less distant ancestors, meaning from the last 5,000 years. Did they eat coconuts or whale blubber? I still believe that Cordain might be right with limited access to fat in the Paleolithic.

    You mention that you are not getting enough calories even with much fat in your diet. But how much is enough? Body adapts and perhaps the energeting needs are not that great? More efficiency, less wastage, better "greasing the gears". As long as you physically and mentally fit. Also, as you observe, temporary increase in energetic demand can be covered by burning your own fat - our critical evolutionary adaptation.

    Re palmitic acid, I would not be afraid of it after weight loss, but the percentage in total fat should more or less reflect our ancestral diet. I will write another post on this, but it appears that different parts of animal have different content of fatty acids (brisket aparently the best!) and that the position of the acid chain (1, 2 or 3) in the fat molecule also matters (which is why milk might be good for babies but not so good for adults and why beef fat could be better than pork).

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  6. Thanks for your response! It does seem to make sense. I'm going to suggest to my mother-in-law that she switch to a more Cordain-ish diet, at least for awhile to see what the effects on weight loss will be (she's not lost an ounce in the last month since going high-fat paleo, and she has much to lose). It seems like -- for whatever reason -- many women don't do well with higher fat diets when it comes to weight loss. Perhaps there is reason for this in our distant past.

    David

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