"There's only one hard and fast rule in running: sometimes you have to run one hard and fast."








Sunday, May 19, 2013

Food craziness, part 4

If you assume from the previous posts that a low level of IGF-1 is a good thing and that a low level of methionine leads to a low level of IGF-1, but a diet that has the bare minimum of methionine in it is not reasonable (and if you're growing or pregnant it definitely is not), you might wonder if there are ways to remove methionine from your bloodstream once you've eaten it.

Interestingly, that's letting IGF-1 do it's job! It facilitates transport of amino acids like methionine from the blood into muscle cells. The way to take advantage of this is through exercise. If you exercise a muscle to failure, you deplete its energy stores; if you then ingest sufficient carbohydrates, the cells store additional energy as glycogen. If you also supply it with protein, the cells can grow and divide and you are depleting the blood of methionine by building muscle. [If you try to deplete the muscle again before resupplying it with fuel, it fails.] This helps to explain the longevity attributed to regular strenuous exercise.

One way that has been shown to dramatically reduce blood IGF-1 levels is intermittent fasting. The liver contains enough glycogen for one day of fasting. On the second day, proteins (particularly enzymes with rapid turnover) are degraded to amino acids and converted into energy, with methionine being converted in part to glucose. On the third day, structural proteins (such as muscle tissue) start getting degraded and the body makes dramatic adaptations to using mostly fats for energy. This process does deplete the blood of methionine and lowers IGF-1, but the effect is temporary. It does suggest, however, that glycogen depletion through exercise will also have this effect.

If one is eating a ketogenic, low-carbohydrate, Atkins-type diet, one may not have enough carbohydrate in one's food to replace the glycogen used by muscle during exercise. These diets are quite high in protein and the protein will supply that glycogen in a process like the one described above, but is unlikely that the level of methionine can be lowered significantly with these diets.

If the level of protein (and hence methionine) is high enough that there is still an excess after the needs for muscle growth and glycogen storage are met, the remainder is converted to fat. This process, too, decreases the level of methionine in the blood, but is certainly not the preferred method for health. Stored fat can only be utilized aerobically - and it takes a lot of exercise to burn a significant amount of fat - so aerobic exercise is another tool to be used.

Finally, some recommendations

This all pulls together into advice you've heard repeatedly:

1) Limit intake of animal products and increase the amount of fruits and vegetables in your diet.
2) Do intense vigorous exercise regularly and get sufficient rest between bouts of exercise.
3) Do a lot of long slow aerobic exercise.
4) Get all the nutrients you need, but don't overeat.


1 comment:

Olga King said...

Thanks for the summary, I checked in and saw so many posts, it was much appreciated to have a short overview! :)