Take every assumption you have about eating, toss it in the garbage disposal, and grind it up with your apple cores and onion skins. Why? An assumption, in many cases, can be what’s holding you back from changing your diet, changing your health—and in effect, changing your life.
Think about how many assumptions you already make about the timing of meals. That if you eat very little during the day, you can feast at dinner. That having chicken breast for breakfast is wacky.
Some of the following principles will fly in the face of the way you may eat now. Change isn’t always easy, but as you begin to practice “chrononutrition”—aligning your food habits with your internal clock—and optimize how you eat for the changing circumstances of daily life and your body, you will begin to feel better.
And that will be the inspiration to make these four guidelines the basis of a new way of eating.
Guideline 1: Eat with the sun
One of the best places to start nudging your biological systems toward good health is in limiting the window of time in which you eat.
• To best maximize chrononutrition, eat only during daytime, or during an approximate 12-hour window (or shorter) every day.
• Try to align when you eat with when your body is ready for food. Your body evolved to be primed for food during the day. And although electricity allows us to extend our days, your body still wants you to eat when the sun shines and fast when the sun sets. Not only does this make sense based on what we know about circadian rhythm, but studies of animals and even a few of people have shown significant benefits to eating only during a limited window. (This does not apply to those in extreme climates with long days or nights.)
The takeaway: Try to eat your daily calories while the sun shines within a 12-hour window. That means no night eating (if you find yourself in a nutritional emergency, reach for some crunchy raw vegetables).
Guideline 2: Eat more early and less later
About 25 percent of people rarely eat breakfast. For those who do, it’s often a quick bite on the go. We’ve all heard the “breakfast is the most important meal” doctrine, but many of us just aren’t hungry in the morning and the demands of the day distract us. Front-load the day with food while your body is the least insulin resistant and your microbiome is ready for a meal. And while it’s better to eat early, it also matters how you eat throughout the entire day.
• Eating breakfast: A few gold-standard randomized trials examine how eating versus skipping breakfast affects weight. The best trial, conducted at Vanderbilt University in 1992, gathered people who normally ate breakfast, as well as people who normally skipped breakfast, and randomly assigned them to keep up their normal habits or switch teams. The study found that people who ate breakfast were less likely to snack and ate less fat throughout the day, though it had no effect on weight loss. Many studies have shown that blood sugar rises or is inconsistent (which is bad for your health as well) throughout the day in people who skip breakfast.
• Less late eating: Not eating breakfast also means that you may eat more later in the day—and that has disadvantages. One study followed more than 1,200 people for six years and found that those who ate a larger percentage of their total daily calories at night had a much greater risk of developing obesity, metabolic syndrome, and a fatty liver compared with those who ate a smaller percentage of their total daily calories at that time.
• Eating early versus eating late: An important 2013 study published in Obesity examined the effect of meal timing on a low-calorie diet plan for women who were overweight. Women were assigned to either eat the largest proportion of their calories early in the day (at breakfast) or late in the day (at dinner). Those who had consumed more of their calories for breakfast lost more weight and inches off their bellies by the end of the 12-week study.
The takeaway: Whether or not it’s the most important meal, the evidence is clear that breakfast should either be your largest meal of the day or your second largest. But sometimes, you don’t have a lot of time in the morning. If that’s the case, make lunch your largest meal. Together, aim to get three-quarters of your daily calories between breakfast and lunch before 2 p.m. Breakfast should be made up of complex carbohydrates (not sugar), protein, and unsaturated fat. Adding protein reduces appetite and food intake later in the day.
Guideline 3: Eat consistently from day to day
Our brains crave novelty—that’s one of the reasons why some of us get excited about new and exotic foods. But our bodies don’t want this today, that tomorrow—ooh, look, a croissant!—they want consistency.
• Get into a consistent rhythm: An interesting study examined what happened to blood glucose and lipids in women who ate either their normal diets with regular frequency or meals and snacks with an irregular frequency for 14 days. Irregular eating led to increased insulin resistance and higher levels of LDL (bad) cholesterol. A different study by the same group found that people who ate regularly burned more calories after meals and had lower total and LDL cholesterol, as well as less insulin resistance.
The takeaway: Try to keep all your meals and snacks the same size every day. One way you can do this is to automate your food choices. Eat the same few options for at least two meals and two snacks a day, so you don’t have to think about what’s healthy.
Guideline 4: Stop stereotyping food
If you want to maximize your health by eating in tune with your circadian rhythm, you have to abandon societal norms around what foods belong with what time of day. As you begin to front-load your day with food, try to rethink what constitutes breakfast and lunch. Instead of adding extra calories early in the day with the usual simple-carb bombs associated with these meals.
• Eat dinner for breakfast or lunch: Ideally, your breakfast and/or lunch should contain protein, fat, and whole grains. Dinner should be light. The ideal dinner is a salad or other green leafy vegetables. Remember, your body is most insulin resistant at night, so you want to avoid simple carbs at dinner. Instead, have fiber-rich vegetables and proteins. The fiber can help you feel full longer, so you’re not tempted to eat after dark.
The takeaway: Plan your meals so that your biggest are the first two of the day, and eat a lighter dinner—a salad with a small portion of protein, for example.
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