Cycling Fuel

Max bodyfat you can burn in an hour is roughly 1 gram per 10 pounds, or in calories, 9 times your weight in pounds.

Anything else is food, muscle glycogen, or actual muscle tissue. Glycogen max is about 4% lean muscle mass, which usually is enough for 90 mins, plus or minus. Food is whatever is in your gut, though exercise slows digestion.

Bonk is when you have used up all food, and your glycogen stores, effectively exercising while fasted.

Bonk power is the max sustained energy ouput when you are fasted/bonked. This is fat burn, and muscle breakdown, combines.

Average watts is roughly 1/4 your calories per hour.

Me as an example
I’m 280 pounds, and bonk power for me is 133 watts, which is about 520 calories per hour. Doing that pretty much guarantees cramps from muscle breakdown.

Biking, I tend to burn 750-850 calories per hour, but I can peak at over 1000 in some instances (beginning, well fed, well rested, very driven).

That’s a big gap, because being big, I get more wind drag, which is 50% of your energy above 15mph. I also take more energy to climb a hill.

Downhill is faster, so less benefit (less time spent going downhill), and often waste the energy by riding brakes so as to not plow through others.

I do best consuming 600 calories per hour while riding more than 90 mins.

So, I have to eat the equivalent of a meal every hour to keep up, and reduce cramp risks. Most of that needs to be carbs that break down in less than an hour. Also, I don’t want to have a bathroom break every hour.

Ride Fuel
Sugary colas have phosphate, glucose, and fructose – all good for refueling. Cookies, sandwiches, etc usually are low roughage, good energy density, and include salt. M&Ms were actually designed to be endurance fuel for the army, and they hold up pretty well in a plastic bag.

Basically, all the things that are bad for you normally make great endurance fuel.

As to proper “race fuel”, honestly, it’s too low calorie for someone my size. Some people only need 200 calories an hour to stay fueled, so half banana, a 2″ square of granola, and a swig of gatorade is fine. For me, that would be a whole bunch bananas, and two quarts of gatorade. Just too much bulk.

Add to all that the need for oxygen to build ATP (actual muscle energy chemical). It takes 35% more oxygen to burn blood glucose than intra-muscular glycogen. Fat takes twice as much oxygen as glucose. High heat, humidity, low pressure, altitude, carbonation, and alcohol all reduce oxygen availability. Transport of glucose into the cell takes ATP. Digestion of food takes ATP.

Diabetes, Insulin Resistance, and Metabolic Syndrome
The key there is to not eat much carbohydrate outside of the exercise times. When glycogen reserves are full (muscles recovered), and adipose cells are replete, then why would you need more fuel? That’s the practical wording of the physiology here, despite the perception of a faulty hunger mechanism for the obese, or lack of islets for type I, or the defective signalling in Type II without obesity triggers.

Exercise induced glucose uptake is normal in diabetic muscle cells:

Exercise may increase glucose sensitivity:

While glycogen is being replenished, glucose uptake by muscles in normal. GLUT4 is transported to the membrane during exercise, even in absence of insulin.

Plastic production vs automobile fuel

A friend and cousin-in-law asked about a photo showing waste plastic bags in woodsy area. The caption indicated that a plastic bag contains enough oil to drive a car 11 meters. I wasn’t sure… This sounded a bit extreme, so I had to research.

It’s a mass thing. A gram of oil makes a gram of plastic. Any waste is used for other plastics, and the catalysts are recycled pretty efficiently in the big shops.

Assuming your car is 20MPG, this is 32187 meters per gallon. Gasoline averages 6 pounds per gallon, or 2722 grams per gallon. That’s 11 meters per gram. I checked, and my plastic shopping bags weigh SIX grams. That would be 66 meters fuel equivalent per bag.

Plastic in the US is made mostly from LPG and NLG, though some raw methane. LPG and NLG have lower energy per gallon, but the same energy per gram. (Energy is released by combining with oxygen, which is based on number of atoms of carbon and hydrogen, which is a mass thing, not a volume thing.) So, gram for gram, it would be the same. 99.45% of the input petroleum is feedstock, and the other 0.55% is fuel for heating, etc.

This seems like a lot, but compare this to paper sacks. It takes 7 times more fuel to deliver paper sacks than plastic sacks. It takes 11 times more fuel to recycle a paper sack than a plastic bag. Finally, 65% of the US reuse their plastic grocery bags, which costs no additional energy. So, each paper sack uses the energy required to push a car 462 meters.

It gets fuzzy on actual production/consumption, but the US used 191 million barrels in 2010, and 416 billion cubic feet of natural gas to product plastic. Worldwide, 280 million tonnes of plastic were produced (2011) and this grows by about 4% per year.

Also, 90% of propane consumed in the US is produced locally.
While the US produces a lot of wood and pulp locally, it’s the #1 importer in the world.

Both paper and plastic calculations here ignore the energy input to produce the feedstock (trees, million year old dead animals). Our biggest problem is not the feedstock for plastic bags (PLA is nice, and biodegradable, made from plant based lactic acid), but our fuel supplies. We desperately need a biofuel with high energy density. Ethanol is a poor choice, and is only in use now because we needed SOMETHING.

Legume oil is about the best we have now. As fuel prices go up, then it becomes more cost effective to use. Algae-Oil would completely reverse our trends. We could supply the planet, plus refill the oil wells. The problem is that it’s delicate, and crops die off too easily to be effective. Selective breeding, crossbreeding, or even direct genetic manipulation may help. Exxon is probably 10 years out from having a commercial production of algal oil. Until then, use of vegetable oil as biofuel continues to cause a huge pressure on foodcrops for impoverished nations.