A new diet has become all the rage in Britain and is now making landfall on our shores as well. It’s called the Fast Diet and millions of weight loss candidates already swear by it.
Like all commercial diet programs, this one promises quick results without much effort and little changes in established eating habits. Followers can eat anything they want for five days but then have to undergo a fasting period of 48 hours where they cannot consume more than 500 to 600 calories per day.
The authors, Dr. Michael Mosley, a medical journalist, and Mini Spencer, a food and fashion writer, claim they both have experienced amazing weight loss successes themselves while experimenting with various forms of intermittent fasting. They also believe their approach can promote overall health and even longevity.
The idea of submitting oneself to periods of food deprivation is nothing new, of course. Our hunter-gatherer ancestors did it, although perhaps not voluntarily, and many religions recommend it as a ritual for cleansing, both physically and spiritually.
“Voluntarily abstaining from eating for short periods of time will allow you to eat what you like, most of the time, and get slimmer and healthier as you go,” the authors proclaim on their website, thefastdiet.co.uk. “The joy of the Fast Diet is that the side-effects are all good,” they say.
But are they?
Even if its true that our bodies are genetically programmed to endure periods of famine, as our forbearers were forced to with regularity when food supplies ran scarce, that doesn’t mean it is a good idea to disrupt your metabolism every so often just to shed a few extra pounds in a hurry.
For example, when the body is subjected to severe calorie restriction, it goes into a different metabolic mode where it switches from burning carbohydrates, its preferred fuel, to burning fat. This may at first sound like a good idea since body fat is what dieters want to get rid off. However, if this process continues for too long, it can lead to a state known as ketosis.
When fat stores become the primary source for fuel, weight loss will occur – but not without side effects. During ketosis, the body builds up substances known as ketones, which can cause a number of health problems. Loss of appetite, nausea, dizziness, irritability, tiredness and bad breath are among the milder symptoms. More serious consequences include dehydration, gout, kidney stones and even kidney failure.
For healthy individuals, short-term ketosis may not carry serious risks. However for diabetics, restricting carbohydrates in their diet may give rise to complications. In extreme cases, ketone levels can become so elevated that a situation develops where high blood sugar is met with a severe shortage of insulin. This is known as diabetic ketoacidosis. The results, if not immediately treated, can be fatal.
Many followers of weight loss diets are plagued with one or more of these conditions. Experimenting with one’s metabolism, especially when done without supervision by a medical professional, can only make matters worse.
Last but not least, there are the long-term implications to be considered. Are we to believe that a five-day period of no dietary restrictions followed by two days of disciplined fasting is a viable option for most people? It seems to me such a regimen bears a strong resemblance to many of the crash diets that may produce quick results but inevitably fail over time.
In response to this latest diet craze, Britain’s National Health System has posted a warning on its website that says, “Despite its increasing popularity, there is a great deal of uncertainty about intermittent fasting with significant gaps in the evidence.”
Timi Gustafson, R.D. is a registered dietitian, newspaper columnist, blogger and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun.” For more articles on nutrition,health and lifestyle, visit her blog, Food and Health with Timi Gustafson R.D. You can follow Timi on Twitter and on Facebook.
