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Medical Fruits make you fat?

  1. Sep 24, 2008 #1
    I read in Harper's Illustrated Biochemistry, that since fruits have fructose and fructose isn't all that well regulated as glucose metabolism they can make you overweight!
    Are there any studies that prove/disprove these?

    For example, fructose can be metabolised without regulation and form excess ATP, NADH etc which favour lipogenesis.
  2. jcsd
  3. Sep 24, 2008 #2


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    The slight difference in metabolism of different sugars is hardly relevant to weight loss. If you eat too many calories, you'll get fat. If you eat fewer, you won't.

    - Warren
  4. Sep 25, 2008 #3

    jim mcnamara

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    Was the section you read discussing glycemic index of foods? Consumption of foods high in high fructose corn syrup increase insulin production, which over very long periods of time may lead to among other things, obesity.

    Warren is right though. In a normal diet fruits are actually a very good thing. IT's the junk food that is the problem. Have not read your source, but it sounds like somebody made a poor choice for an analogy
  5. Sep 25, 2008 #4


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    In fact even junk food is not necesarilly a problem, as long as it is consumed in a reasonable quantities.
  6. Sep 25, 2008 #5
    It is all about calorie intake. If you eat 2 dozen oranges everyday you will get fat. You can eat McDonald's everyday and not get fat. It all depends on calories in vs. calories out. Nutrition wise, it is a much different story.
  7. Sep 25, 2008 #6
    Let's be clear, it's not intake, rather Net Intake (Gross Intake - Energy Spent). Afterall Michael Phelps ate 10,000 calories a day and he has a 6 pack.
  8. Sep 25, 2008 #7
    LIke I said, calories in vs. calories out
  9. Sep 26, 2008 #8
    But if a person ate lots of fruits, due to rapid accumulation of ATP, NADH the body will switch to lipogenesis. This will happen even before the utilsation of that ATP

    However if a person took more glucose, due to regulation of glucose utilisation, the rate of formation of ATP will be slower and hence substantial amounts may get burned off!
  10. Oct 27, 2008 #9


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    By fruit do you mean dessert fruit or botanical fruit? If you actually mean the latter, that includes pumpkin, eggplant, tomato, aubergine, summer squash, legumes, courgette, etc.. Many of these are higher in starch, than oranges, cranberries, plums, & apples; and can increase weight gain. In general, it still comes down to whether you are burning more calories than consuming.
  11. Oct 29, 2008 #10
    fruit in general has very small amounts of fructose. also, some fruits are very low in calories, especially berries such as blackberries, strawberries, raspberries, blueberries, etc. berries are an excellent diet food.

    if a Biochemistry book is warning people not to eat fruit, you should burn that book. that's about as nutty as some bodybuilders and their "clean" eating religion.
  12. Jan 9, 2012 #11
    Actually, Warren, you're incorrect.

    First, with the calories: It depends on the type of calories you're eating and the amount of calories you're burning per day. For example, I used to be a competitive bodybuilder and I would do 10,000 calorie a day bulking phases. My calories were broken down to 45% carbs, 40% protein, and 15% fat. I reached a top weight of 235 pounds at 9% body fat. I was "obese" by BMI standards. Obese with abs. Pretty hilarious. BMI is so obsolete it's ridiculous.

    Second, with types of sugars: Fructose (the natural sugar found in fruits) refills your liver glycogen, which aids in the transportation of nutrients throughout the body (which doesn't take much fructose at all). Consuming too much fructose will overflow your liver glycogen and makes any carb taken in afterwards store immediately as fat instead of being used by the body as energy until the overflow subsides. This is where fruit can make you fat.

    Now, if you're just talking about weight loss, that's easy. You can eat whatever the hell you want and still lose weight. You could eat a bucket of crisco and lose weight as long as you burn more calories than what you take in. Weight loss and fitness and nutrition are two very different industries. The weight loss industry is for idiots who have an obsession with a number on a scale that in no way relects how good they feel or how much energy they have. BMI is how people in the weight loss industry grade themselves. The fitness industry is about composition. Lean mass vs. fat. Here it doesn't matter what the scale tells you. It's all about what the caliper tells you and how much energy you have/how good you feel physically (and, in turn, mentally). The popularity of the weight loss industry far exceeds that of the fitness industry because people are always looking for an easier way and are afraid to work hard to achieve something.
  13. Jan 9, 2012 #12


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    Please post the scientific peer reviewed study in a mainstream journal that says that if you eat more calories than you burn that you won't gain weight.

    Also, please pay attention to the post dates, this thread has been dead for over 4 years.
  14. Jan 9, 2012 #13
    Oh you'll most certainly gain weight. You said "get fat." All dependant on types of calories and fitness rigor.

    I did notice the post dates. I figured I'd try to bring it back to life. Looks like I may be succeeding.
  15. Jan 9, 2012 #14
    Sorry, Warren said that. Not you. My mistake.
  16. Jan 9, 2012 #15


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    Ok, I'll let you slide, but I think chroot meant gaining weight. Others in the thread were using getting fat when they meant gaining weight.
  17. Jan 10, 2012 #16
    Haha thanks. Yeah, I figured. Funny how "weight" automatically means "fat" to most people.
  18. Jan 10, 2012 #17


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    @Cadderiac, since a bodybuilder does gain weight, although his body fat as a percentage of weight may drop, could he also gain fat in absolute terms eventually?
  19. Jan 12, 2012 #18


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    Ok, let's say an average man starts off at 70 kg, 15 % body fat by weight would be 10.5 kg of fat.

    If he becomes a bodybuilder with 8% body fat. To have at least 10.5 kg of fat, he would have to weigh x kg: 8x/100 = 10.5 => x=10.5*100/8 = 131.25 kg.

    That's considerably heavier than Wikipedia's best guess for Arnold's weight of 120 kg. So it seems it could indeed be hard to gain fat by eating more calories of the right type and with the appropriate training.
  20. Jan 21, 2012 #19
    Many fruits are actually quite high in calories because of high amounts of sugar. Natural sugar or not, too much can make you pack on the pounds.

    So it's definitely possible to eat a ton of "healthy" stuff like plums, grapes, etc. and get fat. "but... it's healthy!!!" you say..

    Healthy or not, it's still a lot of calories, and something to consider.
  21. Feb 6, 2012 #20
    Find one person in the United States that became obese by eating too many natural fruits. Honestly, there are bigger fish to fry: sedentary lifestyles and junk food.

    By the way, BMI is a pretty decent indicator for people who aren't body builders. Most people, even most athletic people, do not have to worry about their muscle mass pushing them into an obese BMI level. By decent indicator, I mean it's something the average person can figure out without complex calculations or measurements.
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