Is Intermittent Fasting a Diet Craze or Legit Health Regimen?

The fast diet craze began in the UK in 2012 after medical doctor-turned-journalist Michael Mosley released the BBC documentary titled Eat, Fast and Live Longer. He subsequently wrote the book The Fast Diet (Atria Books, 2013).

This type of eating plan can be carried out in many different ways, such as calorie restriction, intermittent fasting, or alternate day fasting (see sidebar on page 63). All drastically reduce our calorie intake. Mosley’s 5:2 method allows people to eat normally for five days a week, then restricts calorie intake to 500 for women and 600 for men on two or more nonconsecutive days per week. The amount and pace of weight loss will depend on your starting weight.

What to expect

Krista Varady, PhD, is associate professor of kinesiology and nutrition at the University of Illinois. She’s the author of The Every Other Day Diet (Hyperion, 2013) and is behind some of the preliminary human research on the effects of alternate day fasting (ADF). “Most people lose 10 to 30 pounds in eight to 12 weeks by ADF,” she says.

“Larger people lose more per week compared to smaller people … but normal weight people can use ADF to lose the last five to 10 pounds,” she says.

Mosley claims that with his 5:2 method, weight loss is roughly 1 lb (0.5 kg) per week for women and slightly more for men.

Other health benefits

Aside from weight loss, Varady says, “The most notable health benefits of ADF include decreased abdominal fat, LDL cholesterol, triglycerides, glucose, insulin, and blood pressure.”

Study results

In a 2013 study of normal and overweight individuals who followed ADF for eight to 12 weeks, participants experienced a 20 to 25 percent decrease in triglycerides.

Some studies involving daily restriction to 600 calories have shown a normalization of fasting plasma glucose levels in those with type 2 diabetes, improvement of pancreatic function, and reduction of triglycerides.

A 2013 review found that intermittent fasting is easier to stick to than traditional calorie control methods of weight loss.

Intermittent fasting causes a positive impact on the metabolic syndromes associated with heart disease. It may be an easy, cost-effective preventive measure for many people.

A 2013 review in the British Journal of Diabetes and Vascular Disease found that a daily restriction of 600 calories may be too severe for many type 2 diabetes patients, but an intermittent fasting strategy may help improve metabolic parameters and insulin levels and sensitivity, as well as prevent diabetic complications.

The main concern many people have is that they’ll end up bingeing on non-fast days. This is not so, according to Varady. “Most people don’t binge eat during ADF. They only eat 10 percent more than they usually do on the feast day,” she says, although she does stress this has not yet been proven with the 5:2 method. Side effects may include headaches, bad breath, and fatigue within the first two weeks, but these tend to subside within 10 to 14 days.

If you have a medical condition or health concern, consult your health care practitioner before beginning this or any other type of calorie restriction plan or intermittent fasting.