Texas Tech University

Obesity Expert: Study Suggesting Severe Calorie Restriction Lengthens Life Advances Proof of Concept but Provides Few Practical Implications

Glenys Young

April 5, 2018

Nikhil Dhurandhar is an obesity expert with more than 35 years’ experience in nutrition.

Nikhil Dhurandhar
Nikhil Dhurandhar

A recent study from the Pennington Biomedical Research Center shows that when people severely cut their calories – up to 25 percent less than their daily requirement – they can slow their metabolism and possibly slow the aging process.

But Nikhil Dhurandhar, an obesity expert with more than 35 years' experience in nutrition, says such severe calorie restriction could have unintended results, including nutritional deficiencies and greater susceptibility to weight gain if the regimen is not maintained.


Nikhil Dhurandhar, professor and chair, Department of Nutritional Sciences, Texas Tech University,(806) 834-6446 or nikhil.dhurandhar@ttu.edu

Talking points

  • This is a very important study, mainly because it was conducted in humans and over a two-year period – a very difficult feat to achieve.
  • It showed findings that are in line with similar research studies conducted in animals.
  • Some interpretations of these results: 
    • The study was done in non-obese individuals, so the response could be different for those with obesity. 
    • The study does not prove longevity, but it is implied. 
    • While longevity may be a potential benefit, the effects of slowing the metabolic rate may not always be beneficial. A slower metabolic rate may predispose a person to weight gain if the calorie restriction is discontinued or reduced.
    • It's not practical to expect people to eat 15 to 25 percent less than their dietary requirement for a long time. Most people will not.
    • It is unknown what nutritional deficiencies one could get as a result of eating less than what is required by the body.
    • Nonetheless, the greatest value of this study is as “proof of concept.” Rather than expecting people to cut this much food for this long, the study should help in further understanding the underlying molecular mechanism of aging and in eventually developing strategies to counter age-related disorders in more pragmatic ways. 

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