Body Energy Usage

I ponder macro-nutrition needs a whole bunch. Here’s what I have handy, though my technical references are scattered and omitted.

There’s always a need for roughage, vitamins, and minerals, which come from foods with very low calories/kilojoules. Aside from that, the three main macros have specific needs.

A body needs 125 grams of carbs for your brain/nerves; just under 1 gram of protein per kilo of lean body mass to maintain tissues/muscles; and around 30g of fat for cellular and neurological structures. This is usually around 1200 kcal per day, but varies by person 10-20 percent.

Anything else you eat is either poop, or gets converted to sugar. Sugar is burned if it’s needed immediately for exercise (growing, standing, walking, cardio, whatever, anything other than sleeping). Any sugar that is not immediately needed is stored in muscles as glycogen, up to around 4% of your muscle mass. All sugar past that is turned into fat and stored in our fat cells.

This is where “whole grains” comes into play. If it’s not ground up, it takes longer to break it down. However, if you take grains, and mill them into a powder, IT IS NOT WHOLE GRAINS. Just because there is fiber in the food does not mean it’s slow to absorb. The less processed the food, the longer time period over which it trickles energy into your body. If it’s super processed, it all absorbs very quickly, and your body may have trouble figuring out what to do with it unless you’re depleted already.

This is also where some insulin resistance comes from, and why diabetics have normal sugar metabolism in their muscles during exercise, even if they are short on insulin, or are resistant to it. Resistance is GLUT4 which causes glucose receptors to move to the cell membrane, but exercise does the same thing – muscle is hungry, it asks for more. Muscle is not hungry, it asks for less, even if you try to overfeed it. Where would it put this excess sugar? It can only store so much.

During exercise, your fat cells can liberate about 90% of your weight in pounds as usable calories per hour. For me, it’s about 260 calories. The gap is made up from glycogen in the muscles, which is good for just about 90 minutes. If you exercise hard, and stop at 60, and rest for 30, those 30 mins still use up that glycogen for delayed processes, cleanup, etc.

Eating carbs cannot provide as much energy as glycogen, but it’s the next best thing. Also, if you’re fasting, your glycogen reserves get burned up pretty quickly. Glycogen is 3:1 water to sugar, so this is why the first week of dieting is so awesome. No, that’s not fat. It’s muscle energy.

Any energy deficiency not covered by food will be covered by muscle damage. About the same number of calories can be broken down out of injured muscle cells. For me, this is a total of muscle and fat sourced calories of about 520 calories per hour. If I exercise for 3 hours with no food, then my power output drops to 130 watts, which is about 520 calories per hour.

The best option to limit muscle damage, limit recovery time, and optimize exercise benefits when going for more than your glycoge, is to eat as much every hour as you burn, minus the calories that can come from fat. Staying carb focussed can give more energy, and can be easier to absorb, though for some people, this slows the breakdown of body fat.

Staying fat focussed keeps the fat burn mechanisms running, but it takes twice as much oxygen, which means you’re hear-rate limited. It’s less about muscle conditioning then, and more about cardiovascular improvement.

Staying protein focussed is tougher on the kidneys. The aminos have to be converted for use as fuel, and that’s a lot of extra ammonia to pee out. That can be an issue when dehydration might already be at play.

Sugar is not bad for you

Be sure to know what a “Complex Carbohydrate” really is. It doesn’t mean long-chain starches. Those are still sugar. A baked potato, bowl of white rice, a slice of bread, and even corn on the cob are just fast-acting sugars to the body. In fact, they all have a higher glycemic index than table sugar (except some low-carb breads such as Ezekiel bread).

“Complex” means trapped inside of other things. So, an apple is complex. Broccoli is complex. Kale is complex. Peppers, asparagus, etc. You have to chew it, and it has fiber that hasn’t been milled in a factory.

Not apple juice, or any type of juice. As soon as you juice or puree something, even if you “leave the pulp in”, it’s no longer complex. The body no longer has to wait to absorb the calories out of it.

Sitting at a desk, you need about 0.4 kcalories per pound per hour. There is no need to eat anything starchy or sugary. It is turned into glucose before it enters the blood stream, and it only has a half-life of 15 minutes. Anything you didn’t burn in an hour will be turned to fat. Most sugars other than glucose, including half of table sugar, is sent to the liver, converted to glucose, and only about 10% of it makes it into the blood before being turned into fat.

If you’re exercising for 2 hours, you should be able to fuel that with reserves, even at maximum effort. The key is to keep your water and mineral levels happy (20-30oz per hour, with a gram of salt mixed in, and whatever else you want to flavor it). If you want to eat, eat whatever you can stomach.

However, if you’re exercising hard for 5 hours, there is no reason to eat fresh vegetables during your workout. You should have done so before, and will do so after, because of the vitamins and minerals. Those are just too slow to provide your energy needs during cardio.

Exercising at maximum effort, you need about 4 kcalories per pound per hour, plus water and extra minerals. At sustainable effort, you need 3kcal/pound. A tablespoon of corn syrup (not HFCS) washed down with water is almost exactly what you want. (2mg magnesium, 4mg calcium, 9mg potassium, 31mg sodium, 16g glucose, 57 kcal).

Even if you stop for an hour in the middle, you’re still running 30% over idle. If you don’t supplement during the exercise, even with a meal break in the middle, you’ll run out of energy. This will feel like you’re too tired to go on, and if you’re measuring, you’ll lose 30% or more of your peak effort. The refill rate is 3x longer than the burn rate, so once this happens, it’s too late to come back.

Ultra-athletes can double this reserve, and improve their ability to burn fat to extend their peak efforts. Also, their peak efforts move further up, so they can operate at a lower percentage of peak, meaning they can refuel a higher percentage of their reserve consumption during the workout.

Even so, even the best athlete will eventually run out of glycogen reserves. They just have learned how to keep going at this point. They’ve killed off the muscle cells that can’t handle it, and walled off the parts of the brain that tell them they are too tired to continue (fatigue is mostly in the mind if your hydration and electrolytes are okay).

Proof? Look up ultracycling mph ranges. 7hour riders might be in the 17mph range, 12 hour rides in the 16mph range, and 2.5 day rides in the 13.5mph range. Many of these riders can easily average 20mph for 2-3 hour rides, and push 22mph averages for hard workout days. These stats do not subtract rest stops.

Comparatively, my non-athlete speeds, and I did 40mi at 14.8mph, 23mi at 16.3mph, and I can easily hit 18-20mph on flats, even 34mph on a downhill if I don’t have far to go. I *do* subtract out rest stops.