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Nutritionists Reveal The ‘High-Sugar’ Foods You Think Are Healthy That May Actually Cause Fatigue, Weight Gain, And Digestive Issues: Granola, More

January 2, 2026 by Mariam Qayum

 
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When it comes to healthy eating, not everything labeled “nutritious” actually works in your favor. Some foods that seem wholesome on the surface—granola, cereals, and other pantry staples—can quietly contribute to fatigue, digestive discomfort, and even weight gain. Nutrition experts say understanding what’s really in these products and how your body reacts to them is key to avoiding unintended consequences.

Here are some of the “healthy” foods that might be doing more harm than good.

1. Granola

Granola has long been marketed as a fiber-rich, nutrient-packed breakfast option, but not all granolas are created equal. Alanna Kate Derrick, a certified personal trainer and endurance sports nutrition coach, explains that granola can be surprisingly difficult to digest for some people.

"Granolas market themselves as the wholesome, fiber-rich option. But most commercial granolas are also loaded with added sugars and hard-to-digest nuts and seeds that can seriously mess with sensitive stomachs," Derrick says.

For those prone to bloating or digestive discomfort, the combination of sugar and dense ingredients can leave you feeling sluggish instead of energized. Nutritionists recommend opting for minimally processed granola with low sugar content or making your own at home, where you can control the ingredients. Pairing granola with a source of protein, like Greek yogurt, can also help stabilize blood sugar and improve satiety.

2. Sugary Cereals

Cereal aisles are filled with colorful boxes claiming to be healthy, fortified, or whole-grain, but many popular options are loaded with refined grains and sugar. Lisa Richards, a nutritionist and creator of the Candida Diet, highlights why these seemingly simple breakfasts can cause more harm than good.

"These cereals are typically made from refined grains that lack fiber and essential nutrients," Richards explains. "The high sugar content in sugary cereals can lead to a rapid spike in blood sugar levels, followed by a crash, causing inflammation and contributing to feelings of bloating and discomfort."

The result is a cycle of energy spikes and crashes, which can leave you reaching for more quick-fix snacks throughout the day and ultimately contribute to weight gain. Richards recommends choosing whole-grain cereals with minimal added sugar, or skipping cereal entirely in favor of a balanced breakfast with protein, healthy fats, and fiber.

The Bigger Picture

While granola and cereal are only two examples, these issues extend to many foods often considered “healthy.” Highly processed snacks, packaged smoothies, and even some protein bars can carry hidden sugars, refined flours, or other ingredients that spike blood sugar and stress the digestive system. Nutritionists emphasize that the key is not eliminating these foods entirely, but understanding how they affect your body and making informed substitutions.

Opting for whole, minimally processed ingredients, pairing carbohydrates with protein and healthy fats, and reading labels carefully can help reduce fatigue, bloating, and weight gain.

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