Timing your calorie distribution helps with weight management and loss, as well as offer other health benefits — meaning it's not just what you eat but also when you eat it. Distributing your nutrients in an ideal way may help you lose weight, keep it off and be healthier overall.
Chronobiology — All About Timing
Whether your goal is to lose weight, maintain a loss or fuel your active lifestyle, chronobiology — the science of how circadian rhythms affect our body's systems — can reveal a lot about when you should eat for optimal health.
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Depending on your chronobiology, as well as habits such as your bedtime, certain times of the day are ideal for eating to maximize your body's ability to burn off excess calories, use protein and other nutrients to build muscle and provide you with sustained energy.
A July 2018 review published in the journal Metabolism found that circadian misalignment — eating, sleeping, and being exposed to light at unnatural times — had adverse effects on the metabolic health of both animals and human subjects. This left both groups more susceptible to obesity, type 2 diabetes, heart disease and other metabolic conditions.
Early Eaters Lose More Weight
Turns out that breakfast really is the most important meal of the day. A December 2013 study published in the journal Obesity followed a group of women with overweight and obesity over the course of 12 weeks on a calorie-restricted diet of 1,400 calories a day.
Researchers monitored the impact of calorie distribution on participants' weight loss. Those who ate 50 percent of their daily caloric allotment at breakfast, followed by 36 percent at lunch, and 14 percent at dinner, lost 2.5 times more weight over the course of the study than those who ate the inverse.
Both groups were limited to 1,400 calories a day, but the group who ate a higher-calorie breakfast showed greater weight loss and waist circumference loss than the high-calorie dinner group. Moreover, those who ate the bulk of their calories earlier in the day saw better glucose tolerance, lower fasting insulin levels and lower triglyceride levels.
Read more: Lose Weight With These 13 Easy Breakfasts
Prolong Your Overnight Fast
A large-scale September 2017 study published in the Journal of Nutrition followed the meal timing and body mass index (BMI) of 50,660 adults in the U.S. and Canada. The study found that those with a calorie distribution limited to two meals per day with an overnight fast of 18 or more hours showed consistent reductions in their BMIs with those who chose breakfast as their largest meal of the day showing the most benefit.
The study concluded that having a five- to six-hour gap between breakfast and lunch, and then an 18- to 19-hour fast, was an effective strategy for preventing long-term weight gain.
Even if weight loss isn't your goal, intermittent fasting with an emphasis on eating early in the day has been shown to have dramatic health benefits. A June 2018 study published in Cell Metabolism monitored the metabolic changes of a small group of pre-diabetic men with obesity over the course of five weeks.
One group practiced early time-restricted fasting with an eight-hour feeding window and the control group ate their calories over the course of a more conventional 12-hour period. While neither group lost weight, the fasting group had lower insulin levels and improved insulin sensitivity, as well as lower blood pressure.
Read more: How Intermittent Fasting Can Get You Lean
Balance and BMR
If eating the bulk of your calories before noon just doesn't seem feasible for your lifestyle, don't fret. Whether your goal is to lose, gain or maintain your weight, you can achieve it while distributing your calories in the manner that best suits your schedule. Weight management is, first and foremost, a matter of calories in versus calories out.
The USDA defines a healthy diet as "one that provides enough of each essential nutrient from nutrient-dense foods, contains a variety of foods from all of the basic food groups, and focuses on balancing calories consumed with calories expended to help you achieve and sustain a healthy weight." You can achieve that at any time of day by first determining the minimum calories needed per day for your goals.
One way of doing so is to determine your basal metabolic rate (BMR), which refers to the base number of calories your body needs to function optimally with a sedentary lifestyle. You can figure out your BMR by using the following equation:
- Male: (88.4 + 13.4 x weight in kilograms) + (4.8 x height in centimeters) – (5.68 x age)
- Female: (447.6 + 9.25 x weight in kilograms) + (3.10 x height in centimeters) – (4.33 x age)
Once your BMR is established, it should be adjusted to accommodate your physical activity level by multiplying your BMR by the corresponding amounts:
- Sedentary: BMR x 1.2
- Lightly active: BMR x 1.375
- Moderately active: BMR x 1.55
- Very active: BMR x 1.725
The resulting number is the minimum number of calories you should eat a day while trying to lose weight. However, to keep things simpler, you could just use a calorie calculator to do the math and calorie tracking for you.
- Metabolism: "Circadian Regulation of Glucose, Lipid, and Energy Metabolism in Humans"
- Obesity: "High Caloric Intake at Breakfast vs. Dinner Differentially Influences Weight Loss of Overweight and Obese Women"
- Journal of Nutrition: "Meal Frequency and Timing Are Associated With Changes in Body Mass Index in Adventist Health Study 2"
- USDA: "Basic Nutrition FAQ"
- Cell Metabolism: "Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even Without Weight Loss in Men With Prediabetes"