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Benefits and drawbacks of fasting for health

From the print edition

At last the complementary health sector and pharmaceutical industry may have a reason to collaborate. According to a recent study at the University of Southern California, fasting when combined with chemotherapy is a more effective treatment in combating various cancers than either fasting or chemotherapy alone. 

Julie Godfrey

Julie Godfrey

The reason may be that the combination treatment sends healthy cells into survival mode, but it denies cancer cells the nutrients they need to multiply, which causes them to die.  

Fasting is not a new idea when it comes to health. Used in some religions as a way of purifying the soul, it can also take the strain off the body, giving it time to get through a backlog of food and toxin processing. Prolonged fasting does have its drawbacks, though, and it’s not traditionally recommended. Nevertheless, recent headlines have been extolling the virtues of fasting on alternate days and of chronic calorie restriction (defined as the long-term consumption of 15-40 percent fewer calories than usual). 

Apparently this can boost brain function leading to improved memory and a delay in the onset of dementia. Because the cells can become more insulin sensitive, fasting aids in weight management and reduces the risk of developing Type 2 diabetes. Lastly some research suggests that chronic calorie restriction can slow down biological aging of the heart, thus influencing cardiovascular health. 

All this sounds rather appealing and some people may be tempted to try it. But remember, decreasing calorie intake usually decreases metabolism. That’s fine for longevity but if decrease can’t be sustained, problems can arise with weight management. 

If eating less, you need to ensure that what does enter your mouth is bursting with nutrients in order to stay healthy. Be aware, also, that much of the research to date has been on mice and under controlled conditions. Human trials are starting, but the pros and cons won’t be fully understood for several years. 

Meanwhile, the American Cancer Society does not recommend fasting, and any patient who is also diabetic or who has lost a significant amount of weight should consult an oncologist before making such a drastic move. 

While it is not prudent to embark suddenly on either alternate-day fasting or a long-term calorie-restricted diet without first consulting the appropriate medics, it’s also pretty obvious that overeating is a potential health hazard. To avoid it, try to eat mindfully. 

This means serving your food on a plate (or something similar) and sitting down at a table to eat. Keep portion sizes moderate. Put your knife and fork down between mouthfuls and chew very thoroughly, taking your time to really taste and enjoy the flavors. If you feel full, stop eating. If you finish everything but don’t feel satisfied, go and do something else for 20 minutes and only then, if you still feel truly hungry, mindfully eat something small such as a few nuts or a couple more mouthfuls of the main meal. 

Eating and drinking in this way should set you gently and safely on the path to a long and healthy life.

Julie Godfrey BSc (Hons) is a Nutritional Therapy Practitioner and full member of the British Association of Applied Nutrition and Nutritional Therapy (BANT). See or email

News Sources:

Fasting and Cancer, Starving the Beast – The Economist

Fasting Could Help Combat Cancer and Boost Effectiveness of Treatments – Daily Mail

Calories Restriction May Prevent Alzheimers Through Promotion of Longevity Program in Brain – Science Daily

Secret to Long Life: Starve Yourselves on Alternate Days to Boost Brainpower and shed weight – Daily Mail

Additional Sources:

Alternate Day Fasting and Chronic Disease Prevention: A review of Human and Animal Trials – American Journal of Clinical Nutrition

Chronic alternate-day fasting results in reduced diastolic compliance and diminished systolic reserve in rats

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