top of page
  • Dr. David Alfaro

What really fuels you?

When you go for a run or lift some weights, what is actually providing the energy for that to be possible? Are you burning fat? Using glucose? Are you burning a "calorie"?

Well.....yes.....and no.....

The main source of energy the human body uses for pretty much every major reaction, including muscle contraction, is a molecule called ATP (adenosine triphosphate).

Let us talk about ATP.

ATP, as its name indicates, is composed of an adenosine component, and a tail of three phosphate molecules, which store a whackload of energy between the bonds. When a phosphate molecule is cleaved off of the end of ATP, the energy stored in the bond between the phosphates is released. It is this energy that can be used to power all of the many reactions that happen in our bodies every day. The ATP, since it loses a phosphate and only has two remaining, becomes ADP (adenosine diphosphate).

This is where "fat burning" and "carb burning" come in. The body needs to add a phosphate back to ADP in order to replenish ATP stores. We can use the energy within the bonds of sugars and fats to add a phosphate back on to ADP, turning it in to ATP again. Fat burning requires oxygen, so it is occurs best during lower intensity exercise. Carb burning can occur without the presence of oxygen, and therefore can provide energy when intensity levels rise and oxygen levels within the muscles drop.

The burning of fats and carbs, however, are long complicated processes that involve the conversion of larger molecules into smaller ones over various steps, using various enzymes. During very intense exercise, the body needs to replish ATP right away, and the way we do it is with another molecule called Creatine.

Creatine works by grabbing on to phosphate molecules (making Creatine phosphate, aka phosphocreatine), storing the phosphate until an ADP molecule comes around. In a direct reaction, the phosphate that is attached to Creatine is swapped on to ADP, making ATP again. It is a very quick process, which helps us boost ATP to perform explosive exercises such as weight lifting. There are limited stores of creatine phosphate within our muscles, and once they are used up we have to rely on the long winded processes of carbohydrate and fat metabolism to replenish our ATP stores (until more creatine phosphate is created).

Like always, let's ask ourselves some questions about creatine.

Does diet impact creatine levels?

Yes. Creatine is found in muscle cells, so it is plentiful in red meat, fish and other animal proteins. A vegetarian diet results in lower levels of creatine in the blood and muscles, even though our bodies can synthesize it from vegetarian protein sources.

Do creatine supplements increase creatine levels?

Yes. Creatine supplementation has been found to increase intramuscular creatine concentrations in both vegetarians and regular people (hehe... burn).

Creatine is a great supplement for vegan and vegetarian athletes, especially if power is a key component of the sport (eg. crossfit).

Does creatine supplementation improve athletic performance?

The answer to this depends on what we are looking at. Creatine helps with the anaerobic, high intensity components of exercise, so it is great for power lifting, and sports with short powerful bursts of sprinting, such as soccer and hockey.

It may not be the best for long distance runners, who are looking at improving their aerobic capacity and keeping their weight down.

For the everyday athlete who wants to hit the gym, go for a run from time to time and maybe take a fitness class, it is a great supplement. Creatine has been shown to improve maximum strength across various power sports, so it helps you push yourself harder, getting a couple more reps in, or pushing heavier weight.

This is where you get the gains, when you train harder.

Is creatine safe?

There are not many long term studies looking at long term creatine supplementation, but realistically, it is not a long term supplement. The gains you get from Creatine plateau quite quickly, so it is something that should be taken intermitantly (a couple of months on, a couple off).

Short term, the side effects are the common ones for any supplement or vitamin, including upset stomach and nausea.

For a really thorough review of creatine read this:

If you are interested in a pre-workout booster that contains creatine, check this out:

It does not have a crazy amount of creatine in it, like a straight creatine supplement would, but there is evidence that lower doses of creatine are effective. If you are vegan and a power lifter, yea you might look for something with a little more creatine in it. For the regular person who eats meat protein, this is a great level of creatine supplementation to start off with.

Thanks for reading!

Dr. Dave

Featured Posts
Recent Posts
By Category
Search By Tags
bottom of page