Keto question

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If the carbs you eat on a regular diet are used for energy, then, if you eat fat on keto, the body uses the fat you eat for energy? If so, how do you lose existing fat? I'm missing something...

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  • nvmomketo
    nvmomketo Posts: 12,019 Member
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    nvmomketo wrote: »
    MDC2957 wrote: »
    So why do they say keto is so good for burning fat?

    Those who have eaten ketogenic diets for a few months become fat or Keto adapted. This means that they can use fat better or more efficiently during exercise and possibly in times of fasting. Fat oxidation will exceed that of people who eat more carbs when people are matched up by fitness level.

    If you eat too much fat, you will gain weight. This appears to be especially true when one eats high levels of fat when BG is high, and blood insulin levels are high, with a caloric surplus. Fat is very easy to store when insulin levels are high and there is excess calories present.

    Basically, Keto is excellent for burning fat, whether it is body fat or fat in food. Those in ketosis use fat as their primary fuel type.

    If you are using fat "more efficiently," it would mean you need to use less of it to accomplish a given amount of work ("work" in the mechanical sense, which includes exercise). So if it is true that they can use fat better or more efficiently, they would oxidize less fat, not more, than others at the same level of calorie deficit who are not fat-adapted.

    I guess I was not clear on what I meant. Someone who is fat adapted can access more fat, at higher intensities of exercise, relying very little on glycogen and glucose which is often depleted before fat is. Because fat adapted people can access fat better as fuel, they tend to avoid hitting the wall like someone who is more glucose and glycogen reliant.
  • nvmomketo
    nvmomketo Posts: 12,019 Member
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    AnneUT wrote: »
    nvmomketo wrote: »
    MDC2957 wrote: »
    So why do they say keto is so good for burning fat?

    Those who have eaten ketogenic diets for a few months become fat or Keto adapted. This means that they can use fat better or more efficiently during exercise and possibly in times of fasting. Fat oxidation will exceed that of people who eat more carbs when people are matched up by fitness level.

    If you eat too much fat, you will gain weight. This appears to be especially true when one eats high levels of fat when BG is high, and blood insulin levels are high, with a caloric surplus. Fat is very easy to store when insulin levels are high and there is excess calories present.

    Basically, Keto is excellent for burning fat, whether it is body fat or fat in food. Those in ketosis use fat as their primary fuel type.

    This poster is right, and there is science to back it up, but people who have never been on this diet are quick to click "woo". My appetite goes way down when I eat keto. The appetite suppression is another reason the keto diet is effective.

    Just about everybody who says a diet other than moderation may have a benefit, of any sort at all whether science supports it or not, will end up with woo stalkers. Even if you just say it works for you, or you like it, you'll get woo'ed. It's best to ignore it. ;)
  • GaleHawkins
    GaleHawkins Posts: 8,160 Member
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    Sloth2016 wrote: »
    nvmomketo wrote: »
    MDC2957 wrote: »
    So why do they say keto is so good for burning fat?

    Those who have eaten ketogenic diets for a few months become fat or Keto adapted. This means that they can use fat better or more efficiently during exercise and possibly in times of fasting. Fat oxidation will exceed that of people who eat more carbs when people are matched up by fitness level.

    If you eat too much fat, you will gain weight. This appears to be especially true when one eats high levels of fat when BG is high, and blood insulin levels are high, with a caloric surplus. Fat is very easy to store when insulin levels are high and there is excess calories present.

    Basically, Keto is excellent for burning fat, whether it is body fat or fat in food. Those in ketosis use fat as their primary fuel type.

    Not quite.

    A number of adaptations occur in the body subject to reduced carbohydrate intake, called ketosis. These adaptations shift the body from consuming primarily glucose to primarily free fatty acids (FFA) and serve primarily to conserve glucose and nitrogen. (Lyle McDonald, The Ketogenic Diet, p.39). Briefly,

    Because the brain is incapable of using FFA for fuel, the body produces ketones from FFA, which the brain will readily use to derive up to 75% of its total energy requirements from ketones. (L. McDonald, op cit., p. 21)

    By the third day of ketosis, all of the non-protein fuel is derived from the oxidation of FFA
    and ketones. ibid.

    As ketosis develops, most tissues which can use ketones for fuel will stop using them to a significant degree by the third week. This decrease in ketone utilization occurs due to a down regulation of the enzymes responsible for ketone use and occurs in all tissues except the brain. After three weeks, most tissues will meet their energy requirements almost exclusively through the breakdown of FFA. ibid.

    By second week, is marked by decreasing protein breakdown and gluconeogenesis, as the major
    protein sparing adaptations to ketosis occur. (L. McDonald, op. cit. p. 40)

    Muscles will derive up to 50% of their energy requirements from ketones during the first few days of ketosis. However this drops rapidly and by the third week of ketosis, muscles derive less only 4-6% of their energy from ketone bodies. (L. McDonald, op. cit. p. 46)

    Another adaptation occurs in the leukocytes, erythrocytes and bone marrow which
    continue to use glucose, as these tissues cannot metabolize ketones or FFA. To prevent a depletion of available glucose stores, these tissues break down glucose partially to lactate and pyruvate which go to the liver and are recycled back to glucose again. Thus there is no net loss of glucose in the body from these tissues and they
    can be ignored in terms of the body’s carbohydrate requirements. (L. McDonald, op cit. 44)

    The glycerol portion of triglycerides (TG) is converted to glucose in the liver with roughly
    ten percent of the total grams of TG broken down (whether from bodyfat or dietary fat) appearing
    as glucose. (L. McDonald, op cit. 45)

    As ketosis develops, an adaptation in the kidney to prevent excessive nitrogen loss as ammonia in the urine in order to spare protein. As blood ketone concentrations increase, the kidney increases its absorption of
    ketones. If this increased absorption was accompanied by increased ketone excretion, there would be further nitrogen loss through ammonia production. However urinary excretion of ketones does not increase, staying extremely constant from the first few days of ketosis on. Therefore, most of the ketones being absorbed by the kidney are not being excreted. The resorption of ketones appears to be an adaptation to prevent further
    nitrogen losses, which would occur from increasing ammonia synthesis (L. McDonald, op cit. 47).

    Within days of starting a ketogenic diet, thyroid hormone T3 drops quickly. This is part of the adaptation to prevent protein losses and the addition of synthetic T3 increases nitrogen losses during a ketogenic diet (L. McDonald, op cit. 49).

    In sum, the body will adapt to carbohydrate sparsity by three major adaptations: (i) shifting the sourcing of the body's energy needs from carbohydrate consumption to FFA consumption; (ii) producing Ketones for the brain; (iii) conserving glucose by recycling pyruvate for leukocytes, erythrocytes and bone marrow; (iv) reducing protein consumption by producing glucose from triglycerides; (v) increasing uptake of ketone in the kidneys to spare nitrogen loss; (vi) conserving ketones for the brain's consumption by shifting sourcing of muscles' energy needs from ketone to FFA; and (vii) conserving protein requirements by down regulating production of thyroid hormones.

    In conducting these fat adaptations, the body experiencing ketosis conserves sparse glucose and nitrogen resources by using them more effectively.

    @Sloth2016 is the Lyle McDonald in the link below the same one you are talking about?

    https://community.myfitnesspal.com/en/discussion/10635955/lyle-mcdonald-legit-or-fos/p1