This morning as I was getting ready I was listening to a podcast. This podcast was an interview from ultrarunnerpodcast.com. Michael Wardian was talking about his fruit only diet and let me tell you- it was bananas… literally.
This guy is running 100 miles and more a week and eating only fruit. I’m not kidding- only fruit.
I know that fruit is an excellent quick energy source for athletes because of the fast digesting carbs. Here’s some cool science behind it:
When you eat, enzymes in your saliva, stomach, and small intestine break down your food into more simple compounds like amino acids and sugars or polysaccharides. Cells in your small intestine absorb these nutrients so you can get them into your blood and to your organs and muscles. There are enzymes at the border of these cells and your intestine to help break down sugars into simple compounds called monosaccharides. One of these enzymes is lactase, which breaks down lactose. When you are deficient in this enzyme, you can’t break down lactose and the excess sugar in your intestine causes diarrhea, bloating, and discomfort. If you know anyone with lactose intolerance, you will know what I’m talking about!
When the cells in your intestine absorb glucose, they use a transporter that brings in sodium along with the glucose. Fructose uses it’s own system to be absorbed called facilitated diffusion- this means that fructose can just diffuse across the cell without a transport protein like the one for glucose. Fructose then goes to the liver to be processed even more while glucose goes out into the bloodstream to do it’s sugary thing. That is why glucose is the fastest digesting sugar- it doesn’t have to go to the liver like fructose.
When you are in a fed state, your muscles and liver and store glucose in a form called glycogen. In between meals, your body breaks down glycogen to keep glucose going to your blood and brain. Your liver can also make glucose from other compounds like amino acids. When you sleep, your glycogen stores are used up and in the morning you need breakfast to replenish those stores. Some people advocate doing cardio first thing in the morning because without glycogen, your body will be forced to burn up fat for energy. There are pluses and minuses to this theory. Some people are against ‘fasted cardio’ because you will also breakdown some muscle. If you’ve been pumping iron for a few weeks you know how hard it is to gain muscle, so most people don’t want to risk burning it off!
What do you think? Are you a fasted cardio person? Or are you a breakfast first thing person?
All this carb talk got me thinking- is it better to have a diet heavy in protein or carbs? When I’m working out, I focus on eating a higher concentration of protein- but is this really scientifically sound?
In the Journal of Nutrition from the Department of Food Science and Human Nutrition at the University of Illinois at Urbana-Champaign, Illinois, researchers conducted a controlled clinical trial asking the same question I had. The title of the study is, “A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women”. The study followed women adhering to 2 different weight loss diets- either a carb/protein ratio of 3.5 (68g of protein a day) or a ratio of 1.4 (125g protein a day). Each group of women had the same amount of total calories each day and similar amounts of fat. After 10wks, the carb group lost 6.96 lbs while the protein group lost 7.53 lbs. Not a huge difference. But… weight loss in the protein group had a higher loss of fat/lean mass compared to the carb group. The protein group also had significant reduction in triacylglyerols and the ratio of triacylglyerols to HDL (the good cholesterol).
From the abstract of the paper: “This study demonstrates that increasing the proportion of protein to carbohydrate in the diet of adult women has positive effects on body composition, blood lipids, glucose homeostasis and satiety during weight loss.”
In the end, calorie restriction is going to lead to weight loss no matter where the calories are coming from. But if you want the best health benefits, up your ratio of protein to carbs.
I still don’t know what to make of the fruitarian ultra runner… what do you guys think?
Could you live off of watermelon and apples?
Could you run a marathon eating only dates?
I’ll stick to my protein… but don’t worry- I’ll still eat blueberries by the handful every day.
Add to the conversation by commenting below 🙂