Rx Nutrition Resource Center

Rx Nutrition Resource Center

July 02, 2018
5 min read

Part-time diet: Passing fad or for real?

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C Michael White
C. Michael White
Jillian Hyttenhove
Jillian Hyttenhove

A survey conducted by the International Food Information Council revealed that more than a third of Americans follow a specific diet plan, and about one in four said they trust health care professionals regarding which foods to eat or avoid.

These factors suggest primary care physicians have significant opportunities to discuss eating habits with their patients that can significantly affect their overall health, especially considering the increasing incidence of obesity and that ischemic heart disease remains the leading cause of death in the United States.

Against that backdrop, a new eating pattern — the part-time diet — has entered the crowded field of weight loss plans.

To take a closer look at the potential benefits and risks with the new part-time diet, Healio Family Medicine interviewed the diet’s creator, C. Michael White, PharmD, FCP, FCCP of the department of pharmacy practice at the University of Connecticut and Jillian Hyttenhove, MA, RD, a clinical dietitian with the University of North Carolina Health Care system, who was not part of White’s research.

White called his plan “a practical approach to long-term, sustainable weight loss.”

“Patients on the part-time diet actively diet for a period of time and then eat enough calories to neither gain nor lose weight during their resting period,” he said. “The patient should not diet for more than 4 weeks in a row since that is when the biggest metabolism damage occurs. With this diet, the body is not being told there is food scarcity, just that it has eaten a less for a few days, but it will be over soon. It is slower weight loss, it is dull and boring, it takes a long-term commitment, but the studies suggest it works.”

A new eating pattern — the part-time diet — has entered the crowded field of weight loss plans.
Photo source:Shutterstock

White referenced the Minimising Adaptive Thermogenesis and Deactivating Obesity Rebound, or MATADOR trial, to make his point. This trial looked at whether occasional energy restriction improved weight loss efficiency vs. ongoing energy restriction and if so, whether the occasional energy restriction diminished compensatory responses associated with the cutback on energy in two groups.

“At the end of 16 weeks of dieting, the group in the part-time diet regimen lost 10.8 more pounds. After the dieting ended, the previously part-time dieters maintained their weight loss while the previously continual dieters had put back on 3.3 of those pounds,” White said. “The difference in daily calorie burn between the two groups at 6 months? One-hundred and twenty-three calories a day.”


He also referenced a study that appeared in the American Journal of Medicine that followed patients consuming a 1,000 to 1,200 calorie restricted diet daily for 48 continuous weeks versus people who consumed 400 to 500 calories daily for 12 weeks alternating with 1,000 to 1,200 calories daily for 12 weeks before repeating this pattern for the final 24 weeks. Twelve weeks into the study, the group that alternated its eating pattern lost about eight more pounds but after that, there was very little additional weight loss in either group, even though one group had cut twice the number of calories. “It isn’t just about alternating the intensity of dieting, there must truly be a break from dieting to maintain effectiveness, White said. “The body must believe these are momentary blips and not a trend suggesting famine.”

Hyttenhove told Healio Family Medicine that an Endocrine Society Scientific Statement from last year indicated that there is not an abundance of long-term weight loss plans that have proven to be successful, leaving her concerned the part-time diet “may be just another fad.”

“In order to lose weight and keep it off, patients need to change the body’s set point and the body wants to defend that set point. If a patient’s weight drops below the weight set point, their body reduces hormone levels to signal increased appetite, thus resulting in weight gain. In order for long-term, sustained weight loss to take place, you need to lower the weight set point. This can’t be done through calorie restriction or a special diet,” she said.

Hyttenhove discussed a different approach to weight loss that also uses the set point she referenced as a variable.

“To lower the weight set point, individuals need to consume higher quality foods (more fruits, vegetables, whole grains, lean protein, healthy fats), less processed foods and refined grains, exercise, reduce stress, and improve their sleep hygiene. Genetics and certain weight-promoting medications can also play a role in determining one’s weight set point,” she continued.

Hyttenhove acknowledged that the part-time diet does have its strengths.

“I like that the part-time diet isn’t restrictive and doesn’t have forbidden foods like many popular diets. It allows individuals to consume what they like without shame or guilt that they failed. Also, the way it is structured may help people learn how to maintain their weight. Most individuals have a lot of practice losing weight, but struggle with maintaining it. Having the rest periods could help individuals learn what and how much to eat to maintain their current weight.”

Those benefits of the part-time diet come with a catch, and as result, she said she could not recommend that PCPs encourage the eating pattern to their patients.

“However, patients may see the rest days as days to eat whatever they want, leading to a net gain rather than loss. I’m not sure this diet helps people learn to improve their food quality, increase their exercise, reduce their stress, and improve their sleep quality. Losing weight isn’t all about counting calories. If someone doesn’t change their overall lifestyle, the chances of them losing weight and keeping it off are very small,” she continued.

White maintained his diet is a viable and novel option, and noted it can be used in combination with many eating patterns out there such as ketogenic, Mediterranean, intermittent fasting, and the Dietary Approaches to Stop Hypertension, commonly known as DASH.

“The part-time diet is not a short-term fix, it is a slow, flexible transition in lifestyle that provides choices and leads to more sustainable results over time,” he said. “The diet explains to patients using only human clinical trial data why other diets failed so they can see it and believe it. It then offers a ‘not made for TV’ approach to weight loss that is slow and steady over time, explains the benefits of altering what one eats but offers an option to lose weight even if the person doesn’t want to change or cannot afford to change what he or she eats, and offers an option to those who refuse or cannot count calories." - by Janel Miller


Byrne NM, et al. Int J Obes. 2018;doi: 10.1038/ijo.2017.206

Foodinsight.org. 2018 Food and Health Survey. https://www.foodinsight.org/2018-FHS-Report-FINAL.pdf. Accessed June 6, 2018.

Schwartz MW, et al. Endocr Rev. 2017; doi:10.1210/er.2017-00111.

Wing et al. Am J Med 1994;97:354-62.

Disclosures: Hyttenhove reports no relevant financial disclosures. White is author of The Part-Time Diet: Conquer the Weight Loss Plateau and would benefit if the book was sold.