When you eat can be as important as what you eat, according to recent research from Courtney Peterson, PhD, of the University of Alabama, Birmingham. In some of her experiments with early time-restricted feeding (eTRF), animal or human subjects tried consuming most of their calories in the morning and nothing after 3 or 4 PM. Dr. Peterson calls this “eating in sync with our biological clocks.”
Early eating and evening fasting is not a new idea. “Breakfast like a king; sup like a pauper,” is folk wisdom. Buddhist religious orders may eat nothing after noon. Unfortunately, modern society discourages early eating. How can you have dinner at 3 PM when you don’t get off work until 5 PM? How do you eat a big breakfast if you’re rushing yourself and your family out the door to school and work?
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Researchers at Kings College in the United Kingdom noted that modern lifestyles have led to many people dining later in the day, or at irregular intervals, which is confusing the body’s circadian rhythms, interfering with digestion and metabolism of food.
Circadian rhythms are our bodies’ internal clocks. “Every organ has a clock,” said Satchidananda Panda, PhD, of the Salk Institute for Biological Studies. “That means there are times that our livers, intestines, muscles and other organs will work at peak efficiency and other times when they are more or less sleeping.” Circadian rhythms come in three main types: day vs. night, activity vs. rest, and eating vs. fasting. Our cellular clocks expect food at certain times and are ready to produce hormones like insulin and absorb nutrients like glucose at those times. Researchers say that if we eat at times when our bodies are not ready for food, we may not absorb nutrients well. So, for example, after-meal glucose may spike higher if one is eating at a time when cells don’t expect food.
Training our cells
Since our cells do better working in rhythms, we can help them by eating at about the same time every day. This is a challenge for people with hectic lives or those who never formed regular eating habits. We might need to figure out a schedule of eating times that work for us. Irregular “grazing” patterns, in which we constantly have food in our systems, can confuse cells and make themwork less well.
Early time-restricted feeding might be ideal, but it doesn’t fit everyone’s life, and other eating windows can work, too. In Dr. Panda’s studies, participants self-select a 10-hour eating window that works for them. They eat nothing at all outside those 10 hours. A study recently published in the journal Cell Metabolism followed 19 men at risk for diabetes who used time-restricted feeding for a year. They lost weight, reduced fat, and lowered blood pressure, cholesterol and blood glucose. Dr. Panda said most patients were able to stay with time-restricted fasting. Even if they went out of their eating window one or two days a week, they still got benefits. “In mouse studies,” he said “mice who ate in a 12-hour window five days a week still benefited.” Larger human studies are now under way.
Panda’s subjects wore a continuous glucose monitor (CGM) for the first two weeks to prevent low blood sugars. Medications were not changed during the study, but many subjects were able to reduce blood pressure, cholesterol and glucose medications after the study ended.
<h2?When to eat
When is the best window for you? For most people, but not all, eating heavily in the morning is the best match. In many (not necessarily TRF) studies, morning eaters had better insulin sensitivity, lower blood pressure and less hunger than those who ate later.
Bodies do not handle food in the morning the same way they do in the evening. Studies have found that mice who ate at night gained more weight than those who ate the same food in daytime. Women who ate big breakfasts and small dinners had lower insulin and glucose levels; they felt less hunger and lost weight, compared to those who ate light breakfast or skipped the morning meal.
Some people do well with later eating, though. Dr. Panda has also tested “delayed time-restricted feeding” (dTRF), meaning eating from about noon until 10 PM, and found that early and late restricted feeding times both improved insulin response, but only early time-restricted feeding improved fasting glucose levels.
The important thing is to get in a pattern and not eat all day long. Science Daily reported that, “Disturbances in our internal clocks from frequent time zone changes, or irregular working schedules have a significant impact on the development of metabolic diseases including type 2 diabetes.”
Time-restricted eating with diabetes
If you want to try time-restricted feeding, you should work with a doctor, dietitian or diabetes educator about what to eat and what to do about your medicines. Basal/bolus insulin may not change much, but if you’re using NPH or mixed insulin, or sulfonylurea drugs, adjustments will likely need to be made. Other drugs might need to change, too, so keep your doctor informed.
You eat the same total amount on time-restricted feeding as you do when eating all day, just in a shorter time frame. This means (on eTRF) finding time for a big breakfast, which includes some protein and fiber, rather than the typical American refined-carb breakfasts like pancakes and bagels. You can find great information, including ideas on making time for breakfast and breakfast menus at this piece on what to eat for breakfast by dietitian Amy Campbell or this piece on breakfast with diabetes that I wrote.
It might also be difficult to stop eating at 3 PM. Your work or family schedule might interfere. But if you can’t change your schedule, you can move the eating frame later and still get some of the benefits. Or you can be less strict and make your eating frame longer (say, 7 AM to 7 PM), without losing all the advantages of time-restricted fasting.
Getting through the fasting time
I find it hard to get through 15 hours without food, due to a combination of wanting comfort and having feelings of hunger from an empty stomach. Eating more protein and fiber might help with the hunger, and comfort food cravings might ease if we find other ways to relieve stress. Or they might ease with time. We have to make sure we’re getting enough food in our restricted eating time. A dietitian might be able to help with these issues.
Don’t try to be perfect. As Steve Kamb, who prescribes delayed time-restricted feeding, says, “80% adherence that you stick with for a year is better than 100% adherence that you abandon after a month because it was too restrictive.”
Timing our food doesn’t mean we can eat any junk we want. “What you eat still matters,” says Dr. Peterson. But getting your body into rhythm seems to make it work better and feel better. Ask your doctor or educator if you’re interested.