Alternate Day Dieting and Intermittent Fasting: Healthy or Dangerous Fad?


Home / Alternate Day Dieting and Intermittent Fasting: Healthy or Dangerous Fad?

calorie restriction on alternate days may improve health. Image by iprole

The diet industry in the United States is huge – but you don’t need me to tell you that.

Just turn on the television, open a magazine, or look at the ads on social media websites, and it won’t take you long to find an advertisement on diets promising you that this diet is ‘the one.’

There are always new studies being published about diets that promise to shed the pounds and potentially reverse some health conditions; the alternate day diet is one of them – but is it safe or effective?

Diet Every Other Day?

The alternate day diet, also known as Intermittent Fasting, the Up Day Down Day Diet by Dr. Johnson, JUDDD, and a variety of other nicknames, asks the dieter to restrict his calories every other day.

Alternate day calorie reduction studies show benefits such as increased life span, reduced symptoms of arthritis and asthma, and the potential to improve heart disease, Alzheimer’s,  and diabetes.

According to Dr. Johnson’s website, on the restricted-calorie days of the induction phase, dieters should eat no more than 500 calories a day – exact amounts depend on age, activity level, current weight, and other factors. The reduction in calories on alternate days is intended to help stimulate the SIRT1 gene, also known as the ‘skinny gene,’ which is stimulated when calories are restricted, according to Dr. Johnson.

Sound too good to be true? Maybe so, but there is research to back up these claims.

SIRT1 Study

Lab mice that were fed a high fat diet and lacked the SIRT1 protein developed diabetes. Photo by Rama.

More than a decade ago, MIT biology professor Leonard Guarente discovered SIRT1’s longevity-boosting properties and has continued to study SIRT1’s other benefits.  In a more recent study, published in Cell Metabolism, he studied what occurs when SIRT1 is missing from adipose (fat) cells. According to his study, when mice followed a high fat diet, mice that lacked SIRT1 began to develop metabolic disorders like diabetes a lot sooner than mice with the SIRT1 gene.

Professor Guarente told Decoded Science that, according to his research, SIRT1 “can counteract diseases of aging, such as diabetes and Alzheimer’s” – at least in mice. This research shows that the possibility of developing a drug that would enhance the SIRT1 gene in people may help to protect against obesity-related diseases.

Intermittent Fasting: The Problems

Professor Guarente’s research has proven that the SIRT1 protein is essential in protecting mice against metabolic disorders and aging effects, such as Alzheimer’s. However, he told Decoded Science that he disagrees with the alternate day diet – not because of the results, but because of the difficulty involved in following the diet correctly. Guarente believes that a drug could do the same thing as the alternate day diet, but without having to go on a diet.

A variety of additional research has shown other health benefits for intermittent fasting (fasting can be defined as no food intake, anywhere up to 800 calories per day, depending on the source)  – check out the Resources section for several studies on the topic. For Michael Mosley’s adventures in Intermittent Fasting, check out the Eat, Fast, and Live Longer video from the BBC.

The healthiest way to improve your health is by exercising and healthy eating. Photo by the National Institutes of Health.

Registered Dietitian Says “No” to Intermittent Fasting

Research shows that the alternate day diet does turn on the SIRT1 gene, and science confirms that intermittent fasting offers other health benefits, but many experts still disagree. Is this a safe diet, especially for people with diabetes?

Dr. Johnson himself does not recommend alternate day fasting for anyone with Type 1 diabetes, and suggests discussing the diet with your doctor if you have either high or low blood sugar issues, in his book, The Alternate Day Diet.

I interviewed Barbara Day, M.S., R.D., C.N., a registered dietitian with over 30 years of experience, and owner of DayByDay Nutrition, to discuss the safety of intermittent dieting.

I asked her for her thoughts on intermittent dieting and its ability to jump start the SIRT1 gene, and she responded that, “The most current research suggests that increasing energy expenditure (not decreasing energy intake) will increase weight loss.” In other words, exercise, not diet. This doesn’t contradict the SIRT1 research, but does offer another perspective.

In regards to Leonard Guarente’s recent research, and his hope that SIRT1 can be made into a drug to help fight the obesity epidemic, Day responded that obesity drugs are seldom as effective as they seem, and that she believes simply getting exercise and adopting healthy eating habits is a better way to lose weight.

Intermittent Fasting

Research does suggest that the SIRT1 gene is helpful in weight loss, improving some health conditions, and even increasing longevity, but it may not be the answer for everyone. Ask your doctor before making any drastic changes to your diet or exercise level, particularly if you suffer from a chronic condition such as diabetes.


Gribble, K., Mark Welch, D. Life-Span Extension by Caloric Restriction Is Determined by Type and Level of Food Reduction and by Reproductive Mode in Brachionus manjavacas (Rotifera). (2012). Journals of Gerontology. Accessed September 20, 2012.

Klempel, M.C., Kroeger, C.M., Varady, K.A. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cardio-protection as ADF with a low-fat diet. (2012). Metabolism. Accessed September 20, 2012.

Leonard Guarente. High-Fat Diet Triggers Inflammation-Induced Cleavage of SIRT1 in Adipose Tissue To Promote Metabolic Dysfunction. (2012). Cell Metabolism. Volume 16 Issue 2. Accessed September 20, 2012.

Mosley, M. The power of intermittent fasting. (2012). BBC News. Accessed September 20, 2012.

Johnson, J. How to do the diet. (2012). Johnson Up Day Down Day Diet. Accessed September 19, 2012.

Johnson, J. and Laub, D. The Alternate Day Diet. (2008). G P Putnam’s Sons, New York.

Johnson, J., et al. Alternate Day Calorie Restriction Improves Clinical Findings and Reduces Markers of Oxidative Stress and Inflammation in Overweight Adults with Moderate Asthma. (2006). US National Library of Medicine. Accessed September 20, 2012.

Hill, J. Understanding and Addressing the Epidemic of Obesity: An Energy Balance Perspective. (2006). Endocrine Reviews. Accessed September 20, 2012.

Varady, K., Hellerstein, M. Alternate-day fasting and chronic disease prevention: a review of human and animal trials. (2007). American Society for Clinical Nutrition.

Mattson, M.P., Wan, R. Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems. (2005). Journal of Nutritional Biochemistry. Accessed September 20, 2012.

Araki, T., Sasaki, Y., Milbrandt, J. Increased nuclear NAD biosynthesis and SIRT1 activation prevent axonal degeneration. (2004). Science. Accessed September 20, 2012.

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