From personal experience, I can certainly say the afternoon slump is real. One minute I'm happily typing away at my desk, and the next I catch myself staring off into a void, yearning for a pillow, a blanket, and the sweet serenity of a nap. Sometimes the fatigue sets in so quickly that my body feels like it's hit an actual brick wall. With my feet dragging, my eyelids drooping, and a yawn on my lips, I head to the coffeepot for a quick cup of caffeinated revival.
This isn't a problem if it happens occasionally. It is a problem, though, if it happens all the time—like it did for me. You see, for a few months, fatigue set in like clockwork around 1:30, which happens to be the middle of the workday. It also happens to be right after I eat lunch. Upon doing some research (i.e. asking people sitting in my general vicinity), I found that feeling tired after eating is a quite common occurrence. Almost everyone chimed in with an "I hate when that happens" or a "Yeah, why is that?"
I didn't have the answers, but nutritionist and Food Coach NYC & LA founder Dana James did. According to her, it comes down to one of two different things.
"It's not normal to feel tired after eating," James says. "It's the composition of the meal (e.g., it's too high in carbs) or you have a food sensitivity to one of the ingredients, most often wheat. If you don't want to feel tired, drop the bread, grain bowls, pasta, noddles, and sushi rolls and instead focus on loads of vegetables (which are vitalizing) and a palm-size amount of protein. Add a hint of fat to keep you satiated for longer."
So it could be as easy as cutting out carbs (don't shoot the messenger), but if you still experience physical and mental fatigue, ask your doctor about testing for food sensitivities, which can cause inflammation inside the body. As James said, wheat is the most common one, though it could be any type of food.
Last, there's a chance that your fatigue has to do with blood sugar like it did in my case. I was waiting way too long to eat between breakfast and lunch. This led to low blood sugar and fatigue, which hit right after I'd finish eating. Couple that with drinking too much coffee each morning, and I was setting myself up for an epic afternoon slump. Luckily, adjusting my diet and eating more regularly nixed the fatigue issue from my life, but if yours sticks around despite healthy changes, you might need to enlist the help of a supplement, assuming you have your physician's approval. Just remember, as James puts it, "food before supplements," always.
The supplement in question is chromium, which can be taken each day "to stabilize blood sugar levels." James recommends taking 300 mg with both lunch and dinner to control minor swings in blood sugar and, thus, energy. Everyone's a little different, though, so what works for one person might not work for another. Your personal doctor or nutritionist will be able to help you decide what's best before making any big changes to your diet.