You know the feeling. You wake up fine, have your coffee, and get going. Then around two or three in the afternoon, you hit a wall. Your eyes get heavy. Getting anything done feels like a chore.
Most of us blame poor sleep or just getting older. But three registered dietitians say the real culprit is usually what (and how) you are eating.
It All Comes Down to Blood Sugar
Ask three nutrition experts the best habit for keeping your energy steady, and you will get the same answer from all three: keep your blood sugar levels stable.
Kacie Vavrek, RD, a registered dietitian at The Ohio State University Wexner Medical Center, explains it this way. When you eat something high in carbohydrates or sugar, your blood sugar shoots up fast. Your body responds by releasing insulin, which brings it back down, sometimes too far, too fast. That spike-and-crash pattern is what leaves you feeling tired, irritable, and foggy.
Registered dietitian Maggie Michalczyk, RD, puts it simply: “Blood glucose provides energy to our cells. So when our blood sugar levels go up and down, so do our energy levels.” She describes dramatic spikes and crashes as a roller coaster that drains both your brain and your body.
The Simple Fix: Pair Your Foods
So how do you keep blood sugar steady? Registered dietitian Dr. Sonya Angelone, PhD, RDN, says the most effective strategy is pairing carbohydrate-rich foods with protein, fiber, or healthy fats. That combination slows digestion and gives your body a more gradual, steady release of energy instead of a sudden rush.
Michalczyk offers a practical example. Instead of plain toast for breakfast, try adding almond butter, banana slices, and pumpkin seeds on top. That turns a simple carb into a balanced snack with protein, fat, and fiber all working together.
Vavrek recommends leaning on foods naturally high in fiber — whole grains, fruits, and vegetables — and pulling back on ultra-processed foods made with refined sugar, like sugary drinks and packaged pastries. Those refined sugars raise blood sugar much faster than fiber-rich foods do.
Foods That Sneak Up on You
Some blood sugar triggers are obvious: soda, candy, and pastries. But a few surprises are worth knowing about.
- Fruit juice: Even 100% juice with no added sugar can spike blood sugar, according to Dr. Angelone. The reason is that processing removes the fiber. Eating the whole fruit is a better choice.
- Breakfast cereal: Even cereals labeled “whole grain” can be loaded with added sugar, Dr. Angelone says. Check the nutrition label before you buy.
- Granola bars eaten alone: A granola bar by itself can cause a rise and fall in blood sugar. Pair it with something high in fiber, protein, or healthy fat.
- Plain crackers: Both Michalczyk and Vavrek point out that crackers alone can send blood sugar up. Try them with hummus, guacamole, cheese, or tuna instead.
- Alcohol on an empty stomach: Dr. Angelone and Vavrek both note that drinking without eating can cause a significant drop in blood sugar. Having a nutrient-rich snack or meal alongside your drink helps.
Don’t Skip Meals
Both Vavrek and Dr. Angelone stress that skipping meals is one of the easiest ways to let blood sugar drop. When too much time passes between meals, your levels can fall and leave you running on empty.
Dr. Angelone also mentions that some people find it helpful to use a continuous blood sugar monitor to see exactly how different foods affect them throughout the day. If that sounds interesting to you, it is worth asking your healthcare provider about.
The good news? None of this requires a dramatic overhaul of how you eat. Small changes (pairing foods thoughtfully, not skipping meals, cutting back on sugary drinks) can add up to noticeably more energy from morning to evening.