Intermittent Fasting: New Diet Solution or Passing Fad?

[galapogos]

From Cressey's blog

This guest blog comes from Brian St. Pierre, a Cressey Performance staff member who specializes in nutrition. Keep an eye out for more great things from Brian; he's got a lot of excellent ideas and is very well-read.

Intermittent Fasting (IF) seems to be newest dietary fad. IF followers will choose a day or two each week, and on those days, they simply won’t eat for 24 hours. It seems simple, and a lot of people like the idea of giving your body and digestive system a break.

It also stands to reason that eating this way will help you eat less calories and make it easier to maintain a healthy body weight. Seems logical, right? Since IF usually leads to decreased calorie consumption it is often compared to Caloric Restriction (CR).

CR has been shown in a plethora of animal studies to lead to significant improvements in many markers of health and an increase in life span. Extrapolating that data, it would seem that if humans cut their calorie intake by 30-40% we would lead longer, healthier lives. Here arises the problem. In the animal studies with rats, researches observed signs of depression and irritability. With primates, it was even worse (researchers quantified the amount of monkey poo thrown for statistical analyses...okay, not really, but it's an amusing concept for future reference). If they did not consume enough cholesterol, they became violent.

So, angry monkeys aside, if you are willing to be cold, irritable, and prone to depression and flashes of violence, then caloric restriction is for you!

This is supposedly where IF comes in. More animal studies have shown that when animals were forced to fast every other day, but consume all they wanted on the off days, they were able to maintain their body weight, while also sustaining all the life prolonging benefits of CR. They had better glucose tolerance, insulin sensitivity and blood pressure to name a few. It was the best of both worlds!

After these initial animal studies, human researches jumped on the IF bandwagon. People were expecting big things. Unfortunately, they were very disappointed with the results. Research started showing that people following IF, or even purposefully skipping a few meals per day were developing insulin resistance, decreased glucose tolerance, and increased blood pressure. These problems were not tremendous problems and some might argue that in real world IF, where people don’t fast every other day (only once or twice a week), the studied health problems wouldn’t occur.

Even if this is so, there is another problem with which we have to contend. The largest problem is a decrease in thermogenesis. Essentially saying that these people, even though they purposefully consumed as many total calories on IF as the control group, had drastically suppressed their metabolisms. This is why so many people have found such little real world fat loss from IF. In most real world applications - especially because people were eating diets in a significant caloric deficit - the body downregulated its thermogenesis to such an immense degree as to not allow for almost any weight loss. This to me is the final blow.

So, I guess if fasting is your thing, and it's not causing you any negative health effects, then have it. As for me, I prefer to stick to my low carb diet, eat whenever I feel like it, and receive all the benefits that IF proposes to give - except mine are real, not imaginary or hypothetical.

[nimrod69]

Intermittent FAsting(IF) fast for 24hrs?? i tot its 16hrs onli..

Example :
last meal - 2000hrs
Fast 16hrs
1st Meal on nx day - 1200hrs

[Yxy]

also discussed here :

http://www.performancemenu.com/forum/sh ... php?t=3151

I think I'll trial run this fasting thing 2x/wk to see if anything happens

[galapogos]

More at T-Nation

Q: What do you think of intermittent fasting? I've read about some plans that involve fasting for 24 hours every so often. Some plans call for alternate-day fasting. It's said to improve insulin sensitivity and increase longevity, among other benefits. Any thoughts?

A: Many, actually. Are you surprised?

Fasting as a strategy to enhance health has been around since the days of Hippocrates, the dude considered to be the father of modern medicine. It's used by religious orders as a spiritual discipline, and many high-end spas have some form of a fast — often called a "detox" program — as part of their rejuvenation retreats.

"Fasting and detoxification is the missing link in Western nutrition," says my pal Elson Haas, MD, author of The New Detox Diet. Haas has been running detox programs as part of his medical practice for more than 30 years.

"Fasting is the single greatest natural healing therapy I know," he told me. "People need to take a break from their substances. A fast or detox can give the body a rest so it can rebalance."

But a true fast — even for one day — can be really hard on the body. "A more common and liberal definition of fasting would include the juices of fresh fruit and vegetables as well as herbal teas," says Haas. "Fresh juices are easily assimilated, require minimum digestion, and still supply many nutrients. They also stimulate our body to clear wastes. Juice fasting is safer than water fasting since it supports the body nutritionally while cleansing and maintains your energy level."

You probably heard about the whole "alternate day" stuff because of some mice experiments done at the University of California at Berkeley. The researchers basically fasted (read: starved) the poor mice on alternate days, and then allowed them to eat whatever they wanted on the non-fast ("feast") days.

"We found that fasting can reduce cell proliferation rates in skin and breast," lead researcher Krista Varady told me. "That's equivalent to a decrease in both breast and skin cancer risk."

I won't bore you with the details of the research, but they actually found out that you didn't need to do a full-blown fast on the "fast" days to get measurable benefits. You could still consume about 25 percent of your normal food intake on those "fasting" days — about the equivalent of one meal — and still get value.

But don't use fasting as a weight-loss strategy. It never works. Even in the mice experiments, the mice overcompensated for their fast days by overfeasting on the eating days, so that at the end of the week they had consumed the same amount of calories as they normally would.

Since the only strategy that's ever worked to extend life in the lab is calorie restriction, and since some theorists reason that downregulating insulin signaling may be part of the reason, eating fewer calories within the context of a high-nutrient diet makes sense in general.

If you want to take a day off from regular eating every so often and give your digestive system a rest, it's not a bad idea.

[galapogos]

I am largely known as the fasting guy, but what many people don’t know is that when I went back to school in 2006, I went back to “destroyâ€