That mid-afternoon slump hits most of us by 2 or 3 p.m. The natural instinct is to reach for something—a canned soda, a sweetened iced coffee, or a so-called "energy" drink—that promises a quick lift. But according to dietitians, those very beverages are often the reason your energy crashes an hour later. Instead of supporting steady blood sugar and mental focus, they set off a cycle of spikes and drops that leaves you feeling drained.
Below, we break down three common afternoon drinks that registered dietitians recommend skipping—and explain what makes them problematic for sustained energy.
Why your afternoon drink matters for energy
Blood sugar regulation doesn't stop after lunch. When you consume a beverage high in added sugars or refined carbohydrates in the afternoon, your body releases a surge of insulin to manage the glucose. This often leads to a reactive hypoglycemia—a sharp dip in blood sugar—about 30 to 60 minutes later. That dip is what you feel as fatigue, irritability, or brain fog.
Dietitians emphasize that steady energy depends on avoiding large doses of sugar without accompanying protein, fiber, or fat. Drinks that look harmless on the label can be among the biggest offenders.
1. Sugary soda (regular and diet)
It's no secret that a 12-ounce can of regular cola contains around 39 grams of added sugar—roughly 10 teaspoons. But even diet sodas, which use artificial sweeteners, can disrupt energy regulation. Research suggests that sweet taste alone, even without calories, can trigger insulin release in some people, leading to a subsequent dip in blood glucose. Additionally, artificial sweeteners may alter gut microbiota and influence cravings later in the day.
The bottom line: Regular soda provides a rapid sugar rush followed by a predictable crash. Diet soda, while calorie-free, may still trick your metabolism into an insulin response. If you crave something carbonated in the afternoon, dietitians suggest unsweetened seltzer with a splash of lemon or lime.
2. Sweetened coffee beverages
That vanilla latte or caramel frappuccino from the café isn't just coffee—it's a dessert in a cup. A medium-sized sweetened coffee drink can contain 40 to 60 grams of sugar, often combined with whole milk or cream. The caffeine may mask the crash temporarily, but once it wears off, the combined effect of sugar and dairy fat can leave you feeling lethargic.
Dietitians point out that many people also add sugar to their own brewed coffee. A spoonful here and a splash of flavored creamer there can add up to 20–30 grams of sugar per cup without you realizing it.
The bottom line: If you rely on afternoon coffee for energy, skip the syrups and flavored creamers. Opt for black coffee or a splash of unsweetened milk. The caffeine alone provides alertness without the glucose roller coaster.
3. Bottled iced teas and energy drinks
Bottled iced tea might sound healthier than soda, but many commercial varieties are sweetened with high-fructose corn syrup or cane sugar. A 16-ounce bottle often packs 30–45 grams of sugar. Energy drinks, meanwhile, deliver a triple hit of caffeine, sugar, and stimulants like taurine or guarana. The combination can cause a rapid spike in heart rate and blood sugar, followed by a pronounced energy crash and difficulty concentrating.
Some sugar-free energy drinks avoid the glucose spike, but their high caffeine content (often 200 mg or more per can) can still disrupt sleep patterns if consumed late in the afternoon, leading to next-day fatigue.
The bottom line: Unsweetened brewed iced tea (green or herbal) is a far better choice. If you need a lift, consider a short walk or a glass of water before reaching for another stimulant-heavy beverage.
What to drink instead for steady afternoon energy
Dietitians recommend a few simple swaps that support stable blood sugar and sustained focus:
- Water or sparkling water – Dehydration is a common cause of fatigue. Sometimes the afternoon slump is actually thirst.
- Green tea (unsweetened) – Provides a modest dose of caffeine plus the amino acid L-theanine, which promotes calm alertness without the jitters.
- A small protein-rich snack paired with water – A handful of almonds, a hard-boiled egg, or Greek yogurt can steady blood sugar more effectively than any sweet drink.
The key is to avoid large doses of liquid sugar, especially after lunch when your body's insulin sensitivity naturally declines. By choosing smarter afternoon beverages, you can maintain consistent energy right through to dinner—without the 3 p.m. crash.
