Anyone try the "five and two" diet?

Regarding the body going into "starvation mode": as I understand it, several things happen when the body detects a chronic calorie deficit. Fat is mobilized and burned as an energy source. But the body's general metabolic rate slows down as well, so that you're burning fewer calories per day than you normally would. And if you then go to normal caloric intake, the metabolic rate remains low and the calories are stored as fat. It takes several days of caloric intake at normal levels before metabolism returns to normal. This is why professional dieticians often prescribe eating several small meals spaced out across the day--the body sees a steady input of calories and doesn't switch into starvation mode. It's also part of why a combination of exercise (increasing caloric output) as well as diet (decreasing caloric input) is usually more effective than just decreasing caloric input alone.

-Paul W.

That's true, Paul, but I believe glycogen is burned, followed by fat burning. One day (or even two) of 500 calories probably wouldn't be enough to get to burning a great deal of the fat--in that, I suppose one can say the fat is being stored, but I doubt that is an accurate account of what's going on.

Glycogen (aka animal starch) is the storage mechanism for glucose, mainly in muscle tissue and the liver. Active muscle tissue breaks down glycogen into glucose and then ferments the glucose to lactic acid to obtain energy. The lactic acid travels through the blood to the liver, when then builds it back up to glucose, which goes back to the muscle cells. If the muscle tissue is in resting state, it stores the glucose away as glycogen. Under fasting conditions, such as a 500 calorie diet, the liver burns fat to get the energy to rebuild glucose. So glycogen itself isn't really lost in any sense--it's recycled, and fat is burned to get the energy necessary to build the glycogen back up again.

It takes either starvation or really vigorous aerobic exercise to run down the liver's store of glycogen. Distance runners call the initiation of release of the liver's glycogen stores "second wind". They call depletion of liver glycogen "hitting the wall".

-Paul W.

I never said or claimed anything to the contrary, Brian, so I have no idea why you quoted what I said and specifically replied to me.

He was merely adding to your reply to me, Dave.

Yes. Sorry if unclear.

It takes either starvation or really vigorous aerobic exercise to run down the liver's store of glycogen. Distance runners call the initiation of release of the liver's glycogen stores "second wind". They call depletion of liver glycogen "hitting the wall".

-Paul W.

Isn't there also an initial crash when blood sugar levels of glucose are depleted? Cyclist's term is "bonking"

Another trendy concept in bodybuilding is "ketogenic diets" in which you eliminate almost any carbohydrates and rely on fat stores for almost all energy. Advocates claim miraculous results, but having experienced serious bonks on long, hard bicycle rides I am not even sure how one could get into such a ketogenic state without serious suffering.

There has to be a middle ground between these faddish ideas and my current issue with carbs and sugar. I think intermittent fasting seems to be an interesting compromise.

Those on the Atkins diet, which has very low intake of carbohydrates, have episodes of ketosis. I've experienced it myself when fasting. It leaves you feeling like absolute crap. But bodybuilding has the no-pain-no-gain mentality, so they probably wouldn't care. Ketosis stresses the liver and kidneys and the mechanisms for maintaining normal blood and tissue pH. Not a good thing long term.

-Paul W.

The Atkins diet never asked you to stay on no-carb forever. In the version I read the process was: drop to 0 carbs for a week or two, in order to initiate ketosis, then start adding them back until you feel better but ketosis continues.

I guess there is a functionality issue here in that I want to be able to bicycle comfortably and strongly. Going into ketosis would make that difficult. Trust me, I have been in sugar crash mode, and we are talking gulping sugar packs (Gu is the brand) to get up the hill!