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Dr Panda Scientific Research on the Right Time of Day to Eat: A 12-Hour Window for a Healthy Weight

dr panda healthy weight nytimes

Scientists, like mothers, have long suspected that midnight snacking is inadvisable. But until a few years ago, there was little in the way of science behind those suspicions. Now, a new study shows that mice prevented from eating at all hours avoided obesity and metabolic problems — even if their diet was sometimes unhealthful.

Researchers at the Salk Institute for Biological Studies in San Diego and elsewhere began experimenting with the eating patterns of laboratory mice in a previous study. On that occasion, some mice consumed high-fat food whenever they wanted; others had the same diet but could eat only during an eight-hour window. None exercised. The mice that ate at all hours soon grew chubby and unwell, with symptoms of diabetes. But the mice on the eight-hour schedule gained little weight and developed no metabolic problems. Those results were published in 2012.

For the new study, which appeared in the journal Cell Metabolism in December, Salk scientists fed groups of adult males one of four diets: high-fat, high-fructose, high-fat and high-sucrose, and regular mouse kibble. Some of the mice in each dietary group were allowed to eat whenever they wanted throughout their waking hours; others were restricted to feeding periods of nine, 12 or 15 hours. The caloric intake for all the mice was the same.

Over the course of the 38-week experiment, some of the mice in the time-restricted groups were allowed to cheat on weekends and eat whenever they chose. A few of the eat-anytime mice were shifted to the restricted windows midway through the study.

By the end, the mice eating at all hours were generally obese and metabolically ill, reproducing the results of the earlier study. But those mice that ate within a nine- or 12-hour window remained sleek and healthy, even if they cheated occasionally on weekends. What’s more, mice that were switched out of an eat-anytime schedule lost some of the weight they had gained.

“Time-restricted eating didn’t just prevent but also reversed obesity,” says Satchidananda Panda, an associate professor at the Salk Institute who oversaw the studies. “That was exciting to see.” Mice that consumed regular kibble in fixed time periods also had less body fat than those that ate the same food whenever they chose.

Precisely how a time-based eating pattern staved off weight gain and illness is not fully understood, but Dr. Panda and his colleagues believe that the time at which food is eaten influences a body’s internal clock. “Meal times have more effect on circadian rhythm than dark and light cycles,” Dr. Panda says. And circadian rhythm in turn affects the function of many genes in the body that are known to involve metabolism.

To date, Dr. Panda’s studies have been conducted with only mice, but he says the results seem likely to apply to humans. The upshot: Contain your eating to 12 hours a day or less. And pay attention to when you begin. The clock starts, Dr. Panda says, with “that first cup of coffee with cream and sugar in the morning.”

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Dr. Panda?!?!

Dr Panda

So... WHAT we eat matters less than WHEN we eat?

Probably within reason.  If we ate normal healthy choices and amounts during a 9-12 hour window we should be lean and healthy.  This cuts out one of my bad eating habits, snacking in the evening.  I try not to eat after dinner; which I try to have before 8pm.  Works for me ;)

And how many hours we fast, each day.

“Time-restricted eating didn’t just prevent but also reversed obesity.”


Good luck Janill that's a hard habit to break!

Not if you sedate yourself!

So just fall asleep after dinner and you're good?

Sleeping right after eating is probably not good for digestion but it *would* help with overcoming those cravings.

I wonder why the body craves food at night when it should be fasting. 

Foods that have become abundant in our diets that are addictive? 

Oh right, because we crave them independent of hunger or eating cycles. Darn it. 

Eating food earlier in the day is better:

I like that the next section of this page begins with "Geege is right..."

Geege is right.  This is simply a poorly worded study about fasting: "Fast for 12 to 15 hours a day and you'll be fine." is a much simpler way to report the findings.  

Geege also points out another good reason to get plenty of sleep – it sure is easier to fast by sleeping for 12 hours a day.  And that's what I do on longer fasts (like 10 to 30 days).  

But everyone can do just as well by waking and not eating until lunch... or just by being a geezer and only allowing the latest eating you get to do is at the 4:30 to 6:00 pm dinner specials... just make sure to wear your blue-blocker sun glasses and talk about your ungrateful children and fabulous grandchildren.

The fat building (or inability to lose weight reality no matter what you eat) happens because our bodies need time for insulin decrease in our blood and for glucagon levels to increase (prompting ketosis), which then triggers the body to metabolize fat (adipose tissue) for energy.  And then you lose fat and weight.  The more you fast in frequency and duration, the easier it is for your body to function efficiently and the quicker and less painfully (i.e. no hunger cravings, stomach gurgling and headaches) for you as your metabolism drops into ketosis daily.

Eating, or every time you ingest anything (even if it was dirt, pebbles and cardboard or modern fast food totally devoid of nutrition), stimulates nerve receptors in the small intestine that then trigger the pancreas to dump insulin into the blood, which prevents the body from metabolizing fat.  In addition to frequency, the volume of food ingested also correlates to insulin spikes, or peak dosing, in the blood with longer half-life rates of insulin presence.  I can't remember exactly but the pancreas requires either a two or four-hour refractory period before being able to return insulin production to peak levels, so constant eating produces problems for the pancreas as well cellular insensitivity to insulin throughout the body.

That's one of the reasons calories don't matter and most if not all diets are full of bullshit recommendations – 

Any obese or fat person can eat any diet and lose weight, as long as they fast 12 to 15 hours a day. 

But people don't buy diet books with just a single sentence in them and the majority rarely act on simple advice alone.

that was great, rob!  so is breakfast really NOT the most important meal of the day?  i often feel that i do much better if i wait until lunch to break the fast, but then i guess that still makes it breakfast!

Thanks Emily!  Yes, breaking a fast correctly is always very, very important... and being fully awake and body active is one such way of being correctly prepared to break a fast (as opposed to half-asleep).


Every fast, at a minimum, should be considered a necessary ritual of routine hygiene for long life.


Unfortunately for all of us here in the west, breakfast has been sold to us as a profit center for Big Ag, and we as consumers are now expected, if not folklore-ically prescribed, to habitually pound the worst possible food for us (industrially processed, denatured grains) down our gullet immediately after we wake in some sort of illusory fantasy that we absolutely need this raw resource as energy for a productive day – and that is total bullshit.  Profit seeking misinformation from Big Ag and cereal companies is no surprise, but how it all started is...

These persistent inherent conflicts and outright lies of good health being tied to a hearty breakfast is the legacy of C.W. Post, the cereal magnate who invented Grape Nuts and started our whole breakfast cereal debacle over a century ago:


In 1907 Collier's Weekly published an article questioning the claim made in advertisements for Grape Nuts that it could cure appendicitis. Post responded with advertisements questioning the mental capacity of the article's author, and Collier's Weekly sued for libel. The case was heard in 1910, and Post was fined $50,000. 


It gets better...


In early March 1914, Post was believed to be suffering from appendicitis and was rushed via a nonstop train from California to Rochester, Minnesota to be operated on by William and Charles Mayo, regarded as the preeminent surgeons of the day. Upon examination the Mayo brothers deemed Post to be inoperable, however, and the breakfast cereal magnate returned home to Santa Barbara without surgical remedy, still plagued by stomach pain. ... On May 9, 1914, despondent over his ongoing stomach issues, Post took his own life with a self-inflicted gunshot.


PS  Emily, it makes sense why you might feel good waiting until lunch to eat your first meal: when I was a kid I spent long summers working on my aunt's family farm in southern Ontario, Canada... we'd eat a healthy breakfast off our own farm grown fare and it was delicious.  But a hearty breakfast was served well after we'd already been up and working our daily chores, and those usually took a good two to three hours...  and I felt great eating at that time!  

whoa.  the things we believe...

(your farm life sounds heavenly, though!)

grape nuts are so disgusting, they had to make up *something* to sell that crap!  ;)

Amen on that!  lol  What is in Grape Nuts?  certainly not grapes nor nuts :(

Post's first breakfast cereal premiered in 1897, and he named the product Grape-Nuts cereal because of the fruity aroma noticed during the manufacturing process and the nutty crunch of the finished product. In 1904, he followed up the Grape Nuts label with a brand of corn flakes, which was first called Elijah's Manna before being renamed Post Toasties in 1908.

Grape-Nuts is a breakfast cereal developed in 1897 by C. W. Post, a former patient and later competitor of the 19th-century breakfast food innovator, Dr. John Harvey Kellogg. Despite the name, the cereal contains neither grapes nor nuts; it is made with wheat and barley. Post believed that glucose (which he called "grape sugar") formed in the baking process. This, combined with the nutty flavor of the cereal, is said to have inspired its name. Another explanation originates from employees at Post, who claim that the cereal got its name due to a resemblance to grape seeds, or grape "nuts." The cereal originally prepared by C. W. Post when developing the product was a batter that came from the oven as a rigid sheet. He then broke the sheet into pieces and ran them through a coffee grinder to produce the "nut" sized kernels.


Who says being an industrialist isn't an exciting, creative career...kinda like authoring entries for Wikipedia!

Hmmm... I wonder when we're going to reach the event horizon when Wikipedia starts eating it's own tail, such that the sliding social appetite for accepting commentary as fact ends up being the validating reference for future entries... meh, maybe we're already there.  At least with Encyclopedia Brittanica it took decades, generations and plate tectonics to change our view of the past... and that's something we could take comfort in along with afternoon tea... anybody who thinks history is set in stone based on immutable facts either is reading history only once, or not at all.

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