When you eat may be as important as what you eat

Recently, Dr. Satchin Panda sent me a copy of a fascinating paper he and colleagues have just published in the journal Cell Metabolism. Dr. Panda, who is a loyal Obesity Panacea reader, suggested I share the interesting results of the study with our readers. Instead, I thought it would be more fun to interview Dr. Panda about his research so that he could share his findings directly. Hope you enjoy the interview, and see the bottom of the post for details on Dr. Satchin Panda.

PJ: What was the major finding of your study?

SP: Scientists have long assumed that the cause of diet-induced obesity in mice is nutritional; however, our discovery shows that the spreading of caloric intake through the day may contribute, as well, by perturbing metabolic pathways governed by the circadian clock and nutrient sensors. For decades, our society has focused on calorie in, calorie out, exercise and eat healthy, however, this is a novel study that has shown when we eat could be just as important as what we eat.

PJ: Can you briefly describe how the study was conducted?

SP: We put two groups of mice on different eating regiments for 100 days. Both groups ate a high-fat, high calorie diet. The first group was allowed to eat whenever they wanted, grazing throughout the day and night. The other mice had access to food only for eight hours at night, since mice are nocturnal. The results were astonishing. Despite consuming the same amount of calories everyday, the mice that ate on a restricted eight hours were nearly 40 percent leaner and showed no signs of inflammation or liver disease and had healthy cholesterol and blood sugar levels. The group of mice that nibbled day and night became obese, developed high cholesterol, high blood sugar, fatty liver disease and metabolic problems.

PJ: What is the implication of these findings to the average overweight individual?

SP: Our body is designed to undergo overnight fasting. For millions of years humans ate only during the day time. Only recently in the last 50 years our society began eating more at night, and during longer periods throughout the day. Much like our brain needs to rest at night, our data suggests that the stomach and the body’s digestive system need to rest from processing incoming fuel, otherwise we work our organs into a state of metabolic exhaustion. Imagine trying to perform major construction work on a busy highway in the middle of rush hour traffic? Our stomach and liver repairs itself every night, and consuming more food is similar to putting more cars on the road when repairs are being made. It causes a lot of chaos. Researchers may be overlooking the role that timing has on the body’s response to food.

PJ: What is a major limitation of your findings?

SP: The recent study is only conducted in mice. We dont even have an evidence-based measurement of when people eat or know whether eating too many hours correlates with predisposition to metabolic disease.

PJ: Does your research dispute the notion that many small meals throughout the day are the optimal strategy for weight loss or prevention of weight gain?

SP: Our study in mice suggests that an extended fasting time, allowing your stomach and liver to rest may prevent weight gain and metabolic diseases. It does not dispute the notion, as our mice on 8 h eating were still eating frequently.

PJ: What should be the follow-up study to this one? What remains unclear?

SP: Our research needs to be conducted in humans before we could definitively apply it to fight the obesity and diabetes epidemic. However, this study changes the paradigm of our focus on solely calorie-in and calorie out. It brings the notion that our body’s calorie use efficiency can be substanctially changed by eating pattern alone. The effect in humans is unclear. Wheter fasting can also reduce the harmful impact of high fructose and high carb diet needs to be tested. In mice, whether 10,12,14,16 h eating has similar effect also needs to be explored.

PJ: Thanks so much for sharing this fascinating work with us, Satchin.


Dr. Satchidananda Panda is an Associate Professor in the Regulatory Biology Laboratory at the Salk Institute. His research focuses on the effect of biological clock on behavior physiology and metabolism.

Reference: Hatori et al., Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet. Cell Metabolism (2012) doi:10.1016/j.cmet.2012.04.019

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16 Responses to When you eat may be as important as what you eat

  1. Thomas says:

    I wonder how cultural differences in the amount and/or frequency of meals affect the interpretation of the study. Everybody travelling to South-East Asia will notice that people tend to eat throughout the day (and night) – and probably also smaller portions than a big Western meal. One confounder is of course that foods may differ significantly between cultures with different eating habits. I would be happy to hear some informed opinions about this.

  2. Ginny says:

    Actually Thomas, there is a rising obesity epidemic in Malaysia and Singapore and the availability of street foods 24hours a day is being partially blamed for it. Smaller portions of a dish does not hold much weight when people order multiple dishes say, noodles for your individual meal and satay/won tons/ikan bakar to share.

  3. Thanks for yet another fascinating article with a different perspective!

    I recall reading several other articles about nutrition — too busy to look up links right now — which suggested that “ready availability of food” may contribute to obesity. It’s a very typical explanation for obesity. Funny that such sentiments may be right for the wrong reason — it’s not the calories, it’s the timing! Or lack thereof.

    One article bemoaned that, due to ubiquitous marketing for snacks, drive-through fast food and calorie-laden sodas, it has now become socially acceptable [in the U.S.] to eat anytime, anyplace, round-the-clock, everyplace. It quoted an old college professor who was flabbergasted when one of his students brought out a loaf of bread, mustard mayo and bologna, and started making a sandwich from scratch right in the middle of the front row of his lecture hall filled with hundreds of people! Perhaps there’s cultural wisdom behind the old fuddy-duddy nuns and teachers in public schools who would prohibit that kind of behavior and say “I hope you brought enough for _everybody_”…!

  4. Heyjami says:

    So, in trying to put this to the test, should one give up the 8am coffee/cream habit and wait until 10am to start eating/drinking? Then proceed with lunch, and finish dinner by 6pm to keep it within an 8 hour window? I’d like to give it a shot and see if it assists with some of my weight loss/weight maintenance efforts. Is water with lemon slices ok during the non-eating times? Thanks for the post!

  5. You’re not a mouse.

    • Heyjami says:

      Yeah, no kidding, thanks for the reminder. But what an easy thing to explore – eating timing. Not changing nutrients or intake other than timing. I don’t need a research study to explore tools to make myself feel better.

    • BC says:


      What are your thoughts on 8/16 eating windows and EOD fasting? This study aside there is a big push currently in intermittent fasting techniques.

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  7. Katkinkate says:

    It’s definitely worth trying. The only real problem would be fitting it into a family/social routine.

    • Heyjami says:

      Yeah, I have found 8 hours to be impossible (I’m a working mom). 9 hours can be achieved with planning and effort. 10 hours seems more sustainable. And no, early dinners do not make me hungry by the end of the night – it’s been just practicing new habits. Yeah, I’ve heard for years that in order to keep the “metabolism” going you have to eat 6 small meals a day by trainers. This study challenges that. Although, I have to wonder why my labs get fat even though they are fed once per day. And my cats are lean and they are fed continuously. This idea is one puzzle piece to be fit together with many others. The whole weight/lean/etc is such a huge ecosystem in our bodies that I think if there’s anything we’ve learned is that it’s not a simple calories in/energy out, although that may work for awhile.

  8. My trainer would have a fit if I missed breakfast. He has beat into my skull that we are supposed to eat a very specific balance of protein/carbs/fat every 3 hours to keep your blood sugar stable and not spiking. If you ate at 8am and stopped eating at 4pm, you would be pretty hungry by the time you went to bed. My understanding of what life was like, not so very long ago, was that people went to bed REALLY early and got up early to feed the animals, work the farm, etc. With the advent of electricity in every home, radio, etc. people started staying up later which led to eating later in the evening. It wasn’t until the 1970s when food policy changed and more readily available/less expensive food showed up that the average American gained 20 pounds. The gap between going to bed early/stopping eating early and the 1970s is a long time so timing of eating can’t be that related to weight gain. But I have heard it said that you are not supposed to eat anything after 5 or 6 pm if you want to lose weight. Maybe there is something to this study. Wouldn’t hurt to try it. God knows I need to lose weight.

    • BC says:

      There is no shortage of trainers that have fallen behind the times.

      From my understanding fasting and the like are intended in part to increase insulin sensitivity which should reduce the area under the insulin curve in response to a meal. A constantly elevated concentration of insulin in the blood can only lead to deadening the response it elicits.

      I’d question weather a steady influx of calories is necessary when weigh loss is the goal, especially in conjunction with a relatively sedentary life style.

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  11. jan hilborn says:

    I find studies like this intriguing and Heyjami’s observation for her Labs and cats also interesting. But as usual for me, I’m left wondering how those of us who work the graveyard shift fit in. When your work day is 9pm to 9am it’s always hard to figure out when to eat….

    • Nishant says:

      Good point. I just came across this article by chance and am completely from a different field of work. After reading the interview, I was wondering – what would be the results if the nocturnal creatures were put on a strict diet-regime during the day time.
      OR What would be the result if the mice were allowed to nibble through-out the 24Hrs but defined intervals of maybe every 2-3 Hrs. Endless possibilities.