John – I was at your most recent CrossFit Football certification and during the nutrition talk you cautioned us about over-consumption of fruit and more specifically fructose. Can you go into more detail on why I should be weary of fructose ?
Interesting you should ask…I happen to re-working the nutrition portion of the CrossFit Football certification for this weekend in San Francisco…food selection and limiting of fructose is high on my list.
The off-season goal of every football player, and power athlete for that matter, is to get bigger, stronger and faster. We know that increased muscle diameter has direct correlation to getting stronger. In theory, a bigger muscle has the potential to be stronger
With this in mind, how do we create bigger, stronger athletes?
Before everyone blurts out the answer…how does lift heavy weights and eat a significant amount of food sound? Ding, ding, ding, we have a winner.
If you are an athlete trying to gain weight or doing a high volume of training, eating 4000 – 5000 calories is very doable. However, for most people to get consume this amount of food they will have to resort to crap carbs and refined sugars as a means to getting there. Eating a high volume of food is paramount of bigger muscles and the realization that consuming large amounts of sugar has negative and pronounced effects on the body. With high volumes of fructose leading that way to obesity, metabolic derangement, diabetes and cancer.
Eating a high calorie diet where the majority of calories come from sugars, processed foods and gluten is not advisable and, I am totally against it.
A diet of 4000-5000 calories has to be met with significant amounts of meat, fat, and both, green and starchy vegetables. A diet consisting of a minimum of one gram of protein per pound of body weight, fats coming from both saturated and mono-unsaturated and carbs from green veggies and starchy ones like sweet potatoes, yams and turnips. If you are an athlete trying to gain weight or doing a high volume of training, eating 4000 – 5000 calories is very doable. However, for most people to consume this amount of food, they will have to resort to crap carbs and refined sugars as a means to getting there. Eating a high volume of food is paramount for muscle growth and repair. However, consuming large amounts of sugar, especially fructose, has pronounced negative effects on the body. Chronic overconsumption of fructose has been shown to lead the way to obesity, metabolic derangement, diabetes and cancer. Eating a high calorie diet where the majority of calories come from sugars, processed foods and gluten is not advisable and, I am totally against it.
A diet of 4000-5000 calories has to be met with significant amounts of meat, fat, and both, green and starchy vegetables. A diet consisting of a minimum of one gram of protein per pound of body weight, fats in both saturated and mono-unsaturated forms and carbs from green veggies as well as starchy tubers like sweet potatoes, yams and turnips.
Since Chuck Norris received complaints about my usage of his valuable knowledge (you know who you are), I decided to replace it with a TTMJ-approved version of digestion. Last thing you want to do is upset Chuck Norris.
The first major movement occurs when something sweet enters the mouth. The saliva produced contains an enzyme (salivary amylase) that begins to digest the starch from food into smaller molecules. Amylase is an enzyme that breaks starch down into simpler sugars.
Swallowed food is pushed into the esophagus, which connects the throat above with the stomach below. The stomach has three tasks: to store the swallowed food and liquid. Second, mix up the food, liquid, and digestive juice produced by the stomach. Lastly, it empties its contents into the small intestine. Carbs spend the smallest amount of time in the stomach, followed by protein and lastly, fat.
The main hormones controlling digestion are gastrin, secretin, and cholecystokinin (CCK). Gastrin causes the stomach to produce an acid for dissolving and digesting some foods. Secretin causes the pancreas to send out a digestive juice that is rich in bicarbonate, this helps neutralize the acidic stomach. CCK causes the pancreas to produce the enzymes of pancreatic juice, and causes the gallbladder to empty.
Ghrelin is produced in the stomach and upper intestine in the absence of food in the digestive system and stimulates appetite. Free glucose will suppress ghrelin, while fructose has no effect on ghrelin. Peptide YY is produced in the digestive track in response to food and contributes to controlling appetite. The amount of PYY released depends on the macronutrient, protein will stimulate more than fat, and fat will stimulate more than carbs. PYY also regulates food intake, energy and improves leptin sensitivity.
Leptin release is spurred in the stomach in response to the food. Leptin travels to the CNS and signals the body that food has been consumed.
What about fructose?
Fructose can only be metabolized in the liver. The liver can process a decent amount of glucose but it gets full quickly. And while fructose can be used to replenish liver glycogen it does not suppress ghrelin and does not stimulate insulin or leptin secretion. Ghrelin is the hormone that regulates hunger.
So what happens when the liver gets bombarded with fructose and the liver has full glycogen stores?
Once the liver is full of glycogen, the body reacts and starts making fats (palmitic acid) from the fructose and sending them off into the bloodstream as triglycerides.
Excessive amounts of carbohydrates are converted to palmitic acid, a saturated fatty acid; this fatty acid is synthesized into triglycerides and sent into the blood stream. Once palmitic acid hits the blood stream it heads over to the CNS where is does its best to disrupt insulin and leptin signaling.
Everyone is familiar with insulin but what does Leptin do?
Lepin regulates energy intake (appetite) and expenditure. Leptin resistance prevents the brain from detecting its energy reserves or signals of satiety. This results in overeating and changes the body fat mass, which leads to weight gain.
Once liver insulin resistance sets in, the liver becomes a garbage dump releasing glucose into the bloodstream regardless of the levels. The resulting high levels of blood glucose, insulin and triglycerides will stimulate adipocytes (fat cells) to store fat and muscle cells to store glucose as glycogen.
Glucose and fructose become toxic to the cells in high concentrations. Glucose toxicity contributes to the development of diabetes. Long-term effects of glucose toxicity leave individuals with decreased insulin sensitivity. And diabetes develops when insulin production is inadequate for a given level of insulin sensitivity.
How much fructose can the body handle before we start running in to problems?
From my understanding, we can safely process about 50 grams of fructose before things become problematic. That is a pretty low dose of fructose so use the chart below to gauge how much fructose you can consume. We know that problems with fructose are dose-dependent and time-dependent.
There is a table of fruits and sugars on The Paleo Diet listing quantities of sugars in fruits, sweeteners and candies. You can get an idea of which fruits/sugars/foods are highest in fructose, glucose and sucrose. From this you can start to understand where fructose is found in large amounts. Dried fruit is one of the highest on the list (one of the reason we discontinued the sale of beef jerky and dried fruit packs from Paleo Brands), high fructose corn syrup, mangos, apples, oranges, grapes and the amount of fructose in the juice version of these fruits is staggering.
Now let me preface this with… if you are a 145 lbs athlete who eats 1200 calories a day a day and your workouts consist of distance running, metcon and some weights, the problems I have outlined are not as pronounced as an athlete consuming 5000 calories a day with processed carbs, sugars and downing PowerAde or Gatorade before, during and after practice.
By the way ditch the sports drinks; they are packed with high fructose corn syrup!
And thank you Chuck Norris.
This is nearly verbatim of what Mat Lalonde had to say this weekend in Calgary. Pure money.
Chuck Norris and Mat must be friends or at least have studied at the same place.
Both are smart and can count to infinity twice.
Aren’t those tables kind of misleading because sucrose is comprised of one glucose molecule and one fructose molecule bonded, and the body just breaks that bond during digestion? For instance, dates are only comprised of sucrose, but metabolically that is just half glucose-half fructose.
Chuck Norris doesn’t “jump rope.” He repeatedly pushes the planet away from him so his rope o’death can pass unimpeded beneath him.
Misleading HOW? It lists:
It’s not suggesting that this is an additive affair.
Mat Lalonde’s inert atmosphere reactions heal the blind.
Archaeologists are still unsure of how the Dinosuars became extinct; then they realized, Chuck Norris doesn’t like dinosaurs.
Chuck Norris’s cowboy boots are made out of real cowboys.
Like I needed another reason to love sour cherries… Too bad they are so hard to find. Makes sense as to why Kurt Harris calls Apples “sugar bags”. My thanks to Chuck for the explanation. I’ll be bookmarking this for later.
Kind of an aside, but John I was curious of what you think of 80z of chocolate milk for PWO. I’ve read that many crossfitters are a fan of it and,well, it sure tastes yummy and is super-convenient. I washed down my butter/cinnamon baked sweet potato slices w/ it after a WOD today.
It;s remarkably effective… just need to make sure you don;t overdo it. It’ll get ya fat in a hurry.
here is a nifty way to improve it:
buy regular milk, plain coco and granulated dextrose (available online or from most co-ops). Blend it to make the same amount of carbs as in the store bought stuff.
Sucrose, which is what they use to sweeten the regular choco-milk is 1/2 fructose. Dextrose is just another name for…glucose. It will avoid liver glycogen repletion while improving muscle glycogen repletion.
Better living through chemistry.
So when you pick some fruit to eat which should you be looking at? Like how many sugars should we try to stay under. Is it something that should be less then 10 or what.
[…] Fructose […]
What do you think the role of fruit played in our evolution? In the Journal of Nutrition and Metabolism, it was stated humans could handle 16-20grams of fructose a day. While this level is less then what is in a Coke, it does equal about 3-5 pieces of fruit/day.
If you clic on the table to view the whole thing, you will notice that the last column reads “total metabolic fructose”. This is the the free fructose plus half the total sucrose, which gives the total available fructose. The only misleading part is that g/100g do not reflect serving sizes very well. Some fruits become a little better whereas others become a little worse when you look at serving sizes.
I hope everyone likes the TTMJ approved version of digestion as the M@ version I posted was met with whinny and crying. Actually, I am amazed the use of one of my friends and colleagues layout of digestion in this post would lead to such antics. It is not like I was trying to sell his work for my own personal gain…just trying to answer the questions that hit the inbox.
This table is saying that a banana is better to eat than an apple? What is a good # to stay under as far as fructose goes. Finally, if you have a high energy output will relying on fructose to heavliy affect your preformance/health, and are potatoes a better chioce than fruit. Thank you.
Well – this sucks. All the fruit I like is on the high fructose side (probably why I like it). Apples, bananas, cantaloupe, sweet cherries, grapes??!! I’m just glad the list stopped before it got to strawberries.
I’m supposed to eat casaba mellon (what is that?)
We keep fruit around the house. Better to get the kids (yeah, the kids) to eat that then candy or ice cream or any number of other things.
On the sweetners – it looks like a wash for just about anything besides HFCS.
What about having fruit post-wod? I like to hae 1-2 bananas right after I’m done a workout. Is the fructose negligible then?
you know whats under chucks norris’s beard another fist…. great info , what about whey protein and coconut water for pwo , ive been trying that for a couple of weeks. i also usually train in a fasted state at 8:30 am after i get off shift (24hr firefighter) and i dont get to eat for hours , like until 1pm (long comute home).can chuck and the wolf chim in?
[…] Fructose – Talk to me johnnie […]
M@: ahh, I did not open the full table. I retract my previous statement. I always wondered about the serving size thing too, specifically in relation to acid-base balance figures.
[…] Too much of anything can be bad. Too much Paleo can be bad. Fruit you ask? ‘Fraid so. Here is how it breaks down in your body if you binge on the sweet nectar of the gods that is being offered in the fruit section of Whole Foods or any farmer’s market right now. From http://talktomejohnnie.com/diet/fructose […]
Thanks for the post. Very informative.
This is a huge hit. Robb wolf talks about this on the podcast but the chart pulls it all together. For the lean out keep total sugars low but fructose even lower so the meat can work it’s magic. Chuck Norris has an elegant way of summing up a big question. Can he post his thoughts on world peace before the budget deficit gets any bigger? Many thanks
[…] natural sugar found in fruit) needs to be limited if leaning out is your goal. Came across this blog post that explains it pretty well… […]
I just want to point out that you are referring to only one type of diabetes in this article, and that is Type 2 diabetes (often called adult onset diabetes). Type 1 diabetes (often called juvenile diabetes) is an auto-immune disease and can occur no matter how much sugar is consumed.
[…] article: fructose […]
[…] Why You Should be Weary of Fructose […]
[…] geek and i do write some of it down, but i'm obviously not very good at it. lol. This may help too: Fructose Reply With Quote + Reply to Thread « Previous Thread | […]
Hey John, awesome blog man (varied interests), I realise that tomatoes are a fruit despite their decieve-ing-ly vegetable nature but how do they stack up on fructose/sucrose amounts? I love cooking tomatoes, they’re relatively inexpensive and massively tasty (for me anyway); but would they have a fructose load that’s going to “cockblock” my fatloss??
Cheers for the work you do brother 🙂
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