There's an old saying: "Eat breakfast like a king, lunch like a prince and dinner like a pauper." Though the science behind that isn't totally clear, nutritionists agree that dinner should probably be a relatively small meal.

• Why it matters: The American way is the exact opposite, The New York Times' Alice Callahan reports (gift link).

In the U.S., dinner is typically the largest meal — and sometimes the only substantial meal — of the day.

🍗 Zoom in: There's more research on what we should eat to stay healthy than when we should eat. But we do have some clues, Callahan notes.

• People who consume more of their calories in the evening have a higher risk of high blood pressure, Type 2 diabetes and obesity, studies suggest.
• Another study found that people who ate bigger breakfasts were less hungry throughout the day.

⏰ Between the lines: It may come down to your body clock.

• Your body is expecting to digest a big meal — fuel for the day — in the morning. At night, the organs that help metabolize your meals, like your liver and pancreas, slow down.
• So even if you eat the same meal for breakfast and dinner, your blood sugar will see a larger, lingering spike at night compared with the morning. That evening spike can elevate risk of disease and weight gain.

💡 Tips to go: It's not just about increasing the size of breakfast and lunch and shrinking dinner. The timing of your dinner has an effect as well.

• Wrapping up the meal a few hours before bedtime can help your body digest it better — and dodge those blood sugar spikes.
• Plus, walking for 15 minutes after dinner, at just a moderate pace, can lower your blood sugar level — even hours later. Moving in place (when it's too cold out) has similar benefits.

The bottom line: Dinner doesn't have to be the day's smallest meal. But it probably shouldn't be the biggest.

Here's the 12-mile-long John Hopkins Glacier, in Alaska's Glacier Bay National Park and Preserve. Reader Mike Walker tells us he took this photo on an Alaskan cruise with his wife last May.