A new study shows that modest time-restricted feeding works, but why exactly? Let’s dig into it.
Less Time to Stuff Your Fat Face
Time-restricted feeding (TRF) plans are a type of intermittent fasting. Basically, you give yourself a “window” of time in which to eat. Most of these plans, no matter how scientific they try to sound, can be summed up as “skipping breakfast.” So, if you have a snack before bed, sleep 8 hours, then fast until lunchtime, you’ve fasted for about 12 hours.
Some plans have you fasting for 16 hours, which gives you an 8-hour eating window. This may reduce inflammation, “detoxify” the body, and of course lead to some fat loss, provided you don’t go buckwild and eat nothing but syrup-soaked donuts during your eating window.
As long as you don’t have disordered eating tendencies – which turn intermittent fasting plans into very slippery slopes – it can work, at least when done strategically for a short amount of time.
That said, super strict TRF plans (4-hour eating windows) have been shown in two animal studies to backfire, leading to an increase in abdominal fat even though scale weight is lost. (See Fasting – Lose Weight, Gain Abdominal Fat?)
Now some researchers out of the University of Surrey are looking into a kinder, gentler version of time-restricted feeding.
The 90/90 Study
During the 10-week study, participants were given some simple meal-timing guidelines:
Delay breakfast by 90 minutes.
Eat your last meal of the day 90 minutes earlier than normal.
Eat what you want in between.
In a nutshell, their normal eating window was “closed” by 3 hours – 1.5 hours in the morning and 1.5 hours in the evening.
Those following the 90/90 plan lost twice as much fat as the control group which just ate normally.
This was just a pilot study, but here are some takeaways:
The 90/90 group ate what they wanted, what science guys calls “free living” or having “ad libitum” food access, but they did naturally reduce their daily calories. This was partly because they didn’t get to eat in the last 90 minutes before bed, a time when many fall prey to TV snacking. So we could say the results were just a matter of “less time to eat, fewer calories consumed.”
More than half (57%) of the study participants said they wouldn’t want to maintain this plan. Why? Because it’s a pain in the ass socially and tough to work into a normal schedule.
Think about it: Delaying breakfast 1.5 hours may cause your first meal of the day to fall right into the timeslot where you have to be at work, school, or the gym. And moving dinner up 1.5 hours may not work with career schedules or family mealtimes:
“Mommy, why doesn’t Daddy sit down and eat with us?”
“Because he’s on a diet. Also, you’re adopted.”
How to Use This Info
If the 90/90 plan fits your schedule, it may be worth trying, especially if you avoid “free eating” like the regular folks in the study. Instead, keep it clean and pack in the protein, like you’re probably already doing.
Two things to keep in mind if you decide to try the 90/90 plan. Fasted weight training is pretty much counterproductive, so if you train in the morning then break your fast with targeted workout supplements to fuel hypertrophy and recover from training.
Many people just find it easier and more convenient to move this 3-hour fasting time to the end of the day. Multiple studies have shown that not eating 3 hours before bed leads to as much fat loss, or more fat loss, than a 90/90 split plan.
If you’re used to late-night snacking, this may be a test of willpower at first until your appetite signaling mechanisms and behavioral habits adjust, but it’s easier for most people to fit into their normal schedules.
Rona Antoni, Tracey M. Robertson, M. Denise Robertson, Jonathan D. Johnston. A pilot feasibility study exploring the effects of a moderate time-restricted feeding intervention on energy intake, adiposity and metabolic physiology in free-living human subjects. Journal of Nutritional Science, 2018
Kara L. Kliewer, et al. Short-term food restriction followed by controlled refeeding promotes gorging behavior, enhances fat deposition, and diminishes insulin sensitivity in mice. The Journal of Nutritional Biochemistry, 2015