sweet potatoes versus fruit

[Matt Sloan]

It's not just his study, there are many more if you wish to look.

The deal with fructose is that it
totally skips the enzyme PFK-I, which
is the regulatory step responsible for
making sure glycogen stores are full
before fat synthesis is switched on.
Instead of being stored as glycogen,
fructose gets directly converted to fat
by the liver

[Katherine Derbyshire]

Originally Posted by Matt Sloan

You like to challenge people on the whole fruit subject, but when someone give you proof you use the same lame line. If you want to lean out (which you have no problem with) then cut out the fruit. Simple science! As mentioned before Bodybuilders are not cutting out fruit because they don't like it, they cut fruit and other carbs to get shredded.....

As Scott noted, it's pretty much impossible to critique this study because he provides no details whatsoever. Beyond the ones he posted, a couple of other questions spring to mind:

* How much fruit? An apple a day? Or three cases of bananas?
* How fat? One could argue that going from 5% to 7% bf is actually a *good* thing...
* Over what time period?
* Activity levels? Fructose replenishes liver glycogen stores and endurance exercise depletes them, so the exercise mix is highly relevant to the question.
* What else were they eating?

I keep using the same line because people keep failing to address the question.

Note that I am not arguing about the mechanisms of fructose metabolism. I am simply insisting on a little perspective. If someone's diet is otherwise in line -- which especially includes eliminating sources of HFCS -- they don't need to be concerned about moderate consumption of fruit.

A friend of mine tried to give blood the other day and couldn't: the swiss chard she had for lunch that day increased her vitamin K levels and made her blood clot so fast the needle clogged. Does this mean leafy greens cause clotting disorders and shouldn't be eaten?

Katherine

[Katherine Derbyshire]

Originally Posted by Matt Sloan

It's not just his study, there are many more if you wish to look.

The deal with fructose is that it
totally skips the enzyme PFK-I, which
is the regulatory step responsible for
making sure glycogen stores are full
before fat synthesis is switched on.
Instead of being stored as glycogen,
fructose gets directly converted to fat
by the liver

And further down in the article, he says

Fructose metabolites enter
below this step, and thus bypass an important point of regulation. Fructose therefore is more prone to be converted to fat,
while glucose is more prone to be converted to glycogen.

So which is it? Is fructose *always* converted to fat, or simply "prone" to be converted to fat?

Katherine

[Katherine Derbyshire]

For those interested in the actual science, here's a review article from February of this year. The review analyzes 41 different controlled feeding trials comparing the effects of fructose and non-fructose carbohydrates.

http://www.ncbi.nlm.nih.gov/pubmed/22351714 (WFS)

LIMITATIONS: Most trials had methodological limitations and were of poor quality. The weight-increasing effect of fructose in hypercaloric trials may have been attributable to excess energy rather than fructose itself.
CONCLUSION:
Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories. Free fructose at high doses that provided excess calories modestly increased body weight, an effect that may be due to the extra calories rather than the fructose.

Katherine

[Dimitri Dziabenko]

http://www.ncbi.nlm.nih.gov/pubmed/21621801 (WFS)

The effect of two energy-restricted diets, a low-fructose diet versus a moderate natural fructose diet, on weight loss and metabolic syndrome parameters: a randomized controlled trial.

Abstract
One of the proposed causes of obesity and metabolic syndrome is the excessive intake of products containing added sugars, in particular, fructose. Although the ability of excessive intake of fructose to induce metabolic syndrome is mounting, to date, no study has addressed whether a diet specifically lowering fructose but not total carbohydrates can reduce features of metabolic syndrome. A total of 131 patients were randomized to compare the short-term effects of 2 energy-restricted diets-a low-fructose diet vs a moderate natural fructose diet-on weight loss and metabolic syndrome parameters. Patients were randomized to receive 1500, 1800, or 2000 cal diets according to sex, age, and height. Because natural fructose might be differently absorbed compared with fructose from added sugars, we randomized obese subjects to either a low-fructose diet (<20 g/d) or a moderate-fructose diet with natural fruit supplements (50-70 g/d) and compared the effects of both diets on the primary outcome of weight loss in a 6-week follow-up period. Blood pressure, lipid profile, serum glucose, insulin resistance, uric acid, soluble intercellular adhesion molecule-1, and quality of life scores were included as secondary outcomes. One hundred two (78%) of the 131 participants were women, mean age was 38.8 ± 8.8 years, and the mean body mass index was 32.4 ± 4.5 kg/m(2). Each intervention diet was associated with significant weight loss compared with baseline. Weight loss was higher in the moderate natural fructose group (4.19 ± 0.30 kg) than the low-fructose group (2.83 ± 0.29 kg) (P = .0016). Compared with baseline, each intervention diet was associated with significant improvement in secondary outcomes. Reduction of energy and added fructose intake may represent an important therapeutic target to reduce the frequency of obesity and diabetes. For weight loss achievement, an energy-restricted moderate natural fructose diet was superior to a low-fructose diet.

Whooops, disregard immediately! Bad fructose, bad fructose!

[Paulo Santos]

Originally Posted by Matt Sloan

You like to challenge people on the whole fruit subject, but when someone give you proof you use the same lame line. If you want to lean out (which you have no problem with) then cut out the fruit. Simple science! As mentioned before Bodybuilders are not cutting out fruit because they don't like it, they cut fruit and other carbs to get shredded.....

That is a crock of ****. Go to BB.com and that whole train of thought has changed. Years ago, bodybuilders wouldn't eat fruit or drink milk because they thought it was bad to lean out. Not any more. I've been on a cutting phase for a little over 10 weeks and it is all about calories. I'm down 13# and it is mainly fat from my stomach. I eat about 3 pieces of fruit per day along with veggies (I'm still eating mainly Paleo, but I'm not killing myself anymore if I have a bagel with cream cheese once in a blue moon).

Cutting out fruit is a bad idea. Way too many good vitamins to give them up.

[Luke Seubert]

Originally Posted by Katherine Derbyshire

Note that I am not arguing about the mechanisms of fructose metabolism. I am simply insisting on a little perspective. If someone's diet is otherwise in line -- which especially includes eliminating sources of HFCS -- they don't need to be concerned about moderate consumption of fruit.

I have a metabolism that is unusually efficient at converting excess bad carbs, including excess fructose, into body fat. Thus, I have a stronger than normal personal bias against fructose, most especially in the forms of sugar and high-fructose corn syrup. So, as you read the next paragraph, bear in mind that it is written by somebody who is a bit of an anti-fructose bigot.

Katherine's statement above is absolutely correct. If you are otherwise eating a healthy, nutritious, balanced diet; the fructose found in fruit does no harm, while the other nutrients in fruit are highly beneficial. The fructose which people should worry about is found in soda pop, sugary sports drinks, juices, and the many, many processed foods which include a lot of sugar or HFCS. If you minimize consumption of such foods, you can safely eat plenty of fruit in conjunction with lots of other healthy, minimally processed foods.

The only exception to the above advice is for the small percentage of the population who are in various ways fructose intolerant. See the following Wikipedia articles for the details:

• Fructose Malabsorption
• Hereditary Fructose Intolerance

So folks, take it from me, your friendly, neighborhood, anti-fructose bigot. Clean up your diet by eating lots of whole, healthy, natural foods (Paleo if you can ), eat fruit in the same moderation as you do all other foods, and quit worrying about excess fructose consumption, because it is not an issue with such a diet.

[John C Corona]

Originally Posted by Matt Sloan

http://www.parrillo.com/articles/52.pdf

WFS

Heres an idea, lets write an article scaring people away from fruit, and pointing them in the direction of our new SPORTS BAR. For purposes of this post, I will not get into the science behind it, but surely this processed sports bar is soooo much better for me than mangos from my tree. Thanks so much Matt.

[Paulo Santos]

<---------Eating apple shaking head at the nonsense in this thread. Never in a million years did I ever think I would hear anyone say that fruit is bad for you.

[John Papianou]

Paulo, haven't you read Genesis? Fruit is responsible for all the ills in this world.