ARI SHAPIRO, HOST:
Have you ever noticed a few hours after a meal, you start to feel a bit moody, less alert, maybe anxious or even angry? If so, you're not alone. Scientists have been studying this phenomenon in a lot of people. As Michaeleen Doucleff explains, the fix involves learning how to tame your blood sugar.
MICHAELEEN DOUCLEFF, BYLINE: At age 76, Judy Freeman is in great health. She's a well-known potter in Alpine, Texas. She doesn't have diabetes or heart disease. She's not overweight, and she's super active.
JUDY FREEMAN: I work maybe 20 hours a week out in the studio, and I try to walk at least four or five times a week.
DOUCLEFF: But in the past year or so, Freeman hasn't felt like herself. She's been more tired, and she'd like to shed a few extra pounds. So today, Freeman decided to try a new strategy. She's going to wear a continuous glucose monitor for a few weeks.
FREEMAN: Arrow points up, glucose is rising.
DOUCLEFF: The monitor estimates your blood sugar every few minutes and sends the value to your phone, so you can keep track of your blood sugar throughout the day and see how various foods affect it.
FREEMAN: I'm interested in finding out how the glucose levels might affect my ability to lose weight and just how it affects my overall energy level.
DOUCLEFF: She's ready to insert the device. It contains a needle that goes into your skin.
OK, you ready? One, two, three.
(SOUNDBITE OF GLUCOSE MONITOR CLICKING)
DOUCLEFF: Did it hurt?
FREEMAN: I didn't feel a thing - just a little pressure.
DOUCLEFF: Today, anyone can go online and buy a continuous glucose monitor. It costs about $50 and lasts a couple of weeks. Studies have shown that these devices really help people with diabetes, but they're still trying to figure out if they can help people without diabetes, like Freeman.
Sarah Berry is one scientist leading this effort. She's a nutritionist at King's College London and chief scientist at the company Zoe, which sells nutrition plans that use these monitors. She and her colleagues have analyzed data from thousands of people wearing glucose monitors. What they found is that many people are what she calls...
SARAH BERRY: Dippers.
DOUCLEFF: That's right - dippers. Basically, after eating carbohydrates, their blood sugar rises quickly, and then about two hours later, dips low - way low.
BERRY: So you'll have this big increase followed by this big crash.
DOUCLEFF: In one study, Berry and her colleagues showed that these dips can trigger people to overeat.
BERRY: If you are a dipper, those people feel more hungry more quickly. They tend to, on average, eat 80 calories more at their next meal and 320 calories more over a whole day.
DOUCLEFF: Berry and her team published their findings in the journal Nature Metabolism. They also found that dips correlate with moodiness and fatigue, which brings us back to Judy Freeman in Alpine, Texas. The first day she wore the monitor, guess what her blood sugar did a few hours after lunch?
FREEMAN: Sure enough, it had shot up at some point, and then it plummeted down to the lowest point.
DOUCLEFF: Freeman had a huge dip, and during it, she felt anxious - even depressed.
FREEMAN: It's a sinking feeling, like, if I don't get up, I'm just going to stop breathing and die. It was so overpowering.
DOUCLEFF: She says she's had this feeling from time to time, but she never connected it to what she ate. So how can Freeman keep these dips from occurring? Dalia Perelman is a research dietitian at Stanford University. She says, No. 1 - avoid meals and snacks that consist mostly of carbohydrates.
DALIA PERELMAN: Don't eat naked carbs. Eat them with some proteins, some healthy fats.
DOUCLEFF: And with more fiber. So for example, add beans to breakfast, canned fish and nuts to lunch, lentils and seeds to dinner.
No. 2 - don't eat all your carbs for the day at one meal. Sprinkle them across several meals.
PERELMAN: It doesn't matter at the end of the day how many carbs you ate. It matters at the end of the meal.
DOUCLEFF: Finally, nutritionist Karen Kennedy says, at meals, eat the protein and fat first - carbs last.
KAREN KENNEDY: Let's say you have a steak and a salad and a baked potato. If you were to eat the salad and the steak first, then you will see that you don't have as much of a spike or as much of a drop afterwards.
DOUCLEFF: And here's the great part. You don't need to buy a glucose monitor to figure this out. Simply pay attention to how you feel about two hours after a meal. If you get moody, anxious or super hungry, you're probably a dipper.
For NPR News, I'm Michaeleen Doucleff.
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