Stuff and Starve: A Means of Holiday Binging or Healthy Eating?

It’s estimated that around 248 million turkeys are raised, 2.4 billion pounds of sweet potatoes are grown, and 7.5 million barrels of cranberries are harvested a year [1], all for our consumption (and I probably inhaled about half that amount on Thanksgiving alone). Needless to say, I’ve been doing a lot of eating, and a lot of thinking about eating, and I’m thinking I need to get back on my time-restricted feeding schedule (or TRF for short).download

What is time-restricted feeding, you ask? It’s a form of intermittent fasting that limits the timing of food consumption to within an 8-12 hour window in a day. This period is relatively short compared to traditional fasts that can last days to weeks. TRF also differs from classic diets in that the focus is on when you eat rather than what you eat (of course what you eat is important in contributing to health!). So how is it that researchers came to think that the timing of eating should be given more consideration? Let’s go back in time for a sec and look at how this craze came about.

Scientists in the early 1940’s found that when you destroy the hypothalamus via an electrolytic lesion, animals displayed “ravenous eating” behaviors, to the point that some even suffocated because they filled every crevice of their being with food [2]. picture2Unsurprisingly, these animals became greatly obese; when restricted to a controlled amount of food for a 24 hour period, they still ate all of it in less than an hour. This prompted wife and husband team Helen and Jay Tepperman to assess the metabolic effects of eating within this small window of time, by training control rats to also eat their food within an hour. They found that this type of restrictive eating has significant effects on lipogenesis (or fat synthesis) [3], and this work inspired spin-off studies, including one exploring the “Stuff and Starve” feeding model [4]. Fast forward to the late 1960s, groups began investigating the effects of the timing of feeding on overall survival in mice and rats and found that there were specific feeding times that were better or worse for animals on restrictive diets [5-7].

When we think of common diets, restrictive eating comes in the form of controlling calorie intake, managing macro ratios, avoiding animal products, or some combination of all of these. Time-restricted feeding differs in that it focuses on limiting the time window, not necessarily the content – ideally you’re still consuming the normal number of calories. It’s becoming popular because groups have found that it can reverse obesity in mice, and since it’s minimally invasive (as compared to surgery), it could prove to be an extremely simple life change that may have huge health benefits. A low risk, high reward situation gets a lot of people excited. But hold on, we’ve seen fad diets come and go, what makes this one different – what’s the scientific basis?

To look at the effects of restricting eating to specific times of day, we must delve into the field of circadian biology, which involves the study of processes that cycle every 24 hours. At the Salk Institute for Biological Studies, a private science institute located in San Diego, Satchidananda Panda and crew have a history of investigating the molecular mechanisms of circadian clocks and have published papers on the beneficial effects of time-restricted feeding on metabolic disease, age-related cardiac decline, and obesity in both fruit flies and mice. When flies could access food for only 12 hours a day, they slept better, didn’t gain weight, and their rate of cardiac decline slowed [8]. Mice typically become obese and suffer from diabetes and liver disease when fed a high fat diet, however, when placed on TRF they did not! [9] This is hugely exciting because fruit flies and mice share a lot of genetic and physiological features with humans, and this research could help us understand how to prevent or treat these diseases. Of course, the strongest evidence will come from studying TRF in humans. Drumroll please… they’re doing just that! They have a current study that aims to collect people’s daily eating habits with minimal intrusion: participants can log meals simply using an iPhone/Android app. While this particular study may not directly address questions like “does TRF extend lifespan?” or “what is the mechanism by which TRF improves health?”, it will definitely help identify any changes in energy levels, mood, or quality of sleep that correlate with a switch to a TRF style of diet.

After hearing Dr. Panda describe his work in a seminar class at UCSD, I was rather intrigued and naturally decided to conduct my own small-scale, completely biased pilot study on me, myself, and I:


Study Aim: To examine the feasibility of a time-restricted diet.

Methods: I restricted my feeding to between 8 and 12 hours a day, beginning when I ate my first meal. Outside of the feeding window, only water was consumed, and while calories were not strictly monitored, daily intake was estimated to range between 1500 and 1800 calories. See Figure 1 for meal timing.

picture1

Figure 1: Feeding schedule during normal eating vs time-restriction

Results: Successful  restriction of
food intake to 12 hours required careful meal planning. Because the bulk of my afternoon eating was done at work, I found myself having to plan an entire day’s worth of meals, so that I could bring all of it with me and consume everything before I headed home. Further, late night snacking was eliminated, so popcorn and hot cocoa were replaced by water and water.

Discussion: Meal planning during TRF was surprisingly more difficult than expected! However, by using a combo of weekend meal prep and snackable fruits and veggies, it turned out to be completely doable. One of the unforeseen drawbacks was the difficulty in consuming all the food within the allotted time some days. Typically a snack of grapes and granola can be filling, but during TRF there were times I was eating in spite of being full, to avoid being hungry later. It was a delicate balance between maintaining a target calorie count overall, but not feeling too full at any given time. One great benefit that occurred was that TRF greatly improved my morning routine. I would wake up hungry, having fully fasted the previous 12 hours or so, and since I have always been morning-averse, finding myself jumping out of bed for breakfast felt like a small miracle!


 

As you can imagine, I was rather keen to share my findings, however, inviting people over for dinner at their normal eating hours proved difficult, as I was eating my last meal of the day in the office at 5pm. Turns out, Dr. Panda’s research suggests that the effects are flexible enough to account for weekend binges, so you can keep a [fairly] strict schedule during the weekdays (okay, doable) and go crazy on the weekend (done and done).

sleepeater1All in all,TRF makes sense: on earth we’re exposed to a predictable, 24 hour rhythm of light and dark. Over time humans have evolved to function during light periods and sleep at night, so unless you’re a sleep-eater this also means that your metabolism is geared up and ready to go when you’re awake and eating, and less so when you’re asleep. The suprachiasmatic nucleus (SCN), also called the central pacemaker, is the part of our brain that regulates the timing of internal processes and has direct connections to the hypothalamus, which controls the release of many neurohormones. Since TRF improves the functions of the internal clock, this may in turn strengthen  a range of physiological rhythms.

After going rogue on my own TRF adventure, I decided to sign up for Dr. Panda’s study, knowing that with some preparation and a little discipline, it’s completely doable. In the endless pursuit of health and happiness, the jury may still be out on the effects of time-restricted eating, but I tend to think that a little stretch of planning and self-discipline is a small investment that could lead to potentially large payouts. Personally, this year’s Thanksgiving feasting has left me in a state of inspired, intermittent fasting. If this speaks to you as well, check out the Panda Lab website, sign up for their 14 week study, and download the app to participate. Happy eating!

 

References:

[1] http://www.statisticbrain.com/thanksgiving-statistics/

[2] Brobeck, John R., Jay Tepperman, and C. N. H. Long. “Experimental hypothalamic hyperphagia in the albino rat.” The Yale journal of biology and medicine 15.6 (1943): 831.

[3] Tepperman, Jay, and Helen M. Tepperman. “Effects of antecedent food intake pattern on hepatic lipogenesis.” American Journal of Physiology–Legacy Content 193.1 (1958): 55-64.

[4] Hollifield, Guy, and William Parson. “Metabolic adaptations to a “stuff and starve” feeding program. I. Studies of adipose tissue and liver glycogen in rats limited to a short daily feeding period.” Journal of Clinical Investigation41.2 (1962): 245.

[5] Stevenson, J. A. F., et al. “Food Restriction and Lipogenesis in the Rat.” Experimental Biology and Medicine 116.1 (1964): 178-182.

[6] Beaton, J. R., et al. “Meal-eating and lipogenesis in vitro of rats fed a low-protein diet.” Canadian journal of physiology and pharmacology 42.5 (1964): 665-670.

[7] Nelson, W., L. Cadotte, and F. Halberg. “Circadian timing of single daily “meal” affects survival of mice.” Experimental Biology and Medicine 144.3 (1973): 766-769.

[8] Gill, Shubhroz, et al. “Time-restricted feeding attenuates age-related cardiac decline in Drosophila.” Science 347.6227 (2015): 1265-1269.

[9] Hatori, Megumi, et al. “Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet.” Cell metabolism 15.6 (2012): 848-860.

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