Doctor Warns Against Common Diet Selection Mistake

Nearly half of Americans are trying to shed pounds each year, with approximately 43 million adults following specialized diets such as keto, vegan or Mediterranean plans, according to recent data. But amid the maze of conflicting nutritional advice, determining the optimal eating pattern remains a challenge for many.

Dr. Mark Hyman, a prominent physician, suggests there’s no universal solution for healthy eating. “The truth is the best diet is the one that works for your biology,” he explained on a recent episode of “The Dr. Hyman Show.” “We’re all different. There isn’t a one-size-fits-all diet.”

At the foundation of any effective nutrition plan, Hyman distinguishes between genuine food and what he terms “food-like substances.” This fundamental difference shapes how our bodies respond to what we consume.

“Food is something that helps support the health and development and growth of an organism,” Hyman said. “Honestly, what most people are eating in America today is not definitionally food. It’s a food-like substance.”

The distinction goes beyond semantics. Minimally processed foods—items recognizable and close to their original form—function differently in the body compared to ultra-processed products engineered primarily for convenience and extended shelf life.

Hyman takes his definition further, emphasizing that “food is medicine.”

“It’s not like medicine. It is medicine,” he clarified, pointing to the thousands of bioactive compounds in plants that influence inflammation, detoxification and disease risk. “Everything you put in your body is a drug that’s going to help you or harm you,” he added, noting that every meal impacts bodily functions.

Blood sugar regulation stands as a critical factor determining how individuals respond to different foods. Diets high in refined starches and sugars can disrupt metabolic health with far-reaching consequences, according to Hyman.

“If you don’t have balanced blood sugar, if you have high blood sugar or high insulin, this is going to screw up your blood sugar metabolism,” he explained. These metabolic disruptions extend beyond diabetes and heart disease to potentially impact mental health conditions as well.

This metabolic connection helps explain the popularity of ketogenic diets, which emphasize high fat, moderate protein and minimal carbohydrates. By dramatically reducing carbs, the keto approach shifts the body from burning sugar to burning fat, a state known as ketosis.

Hyman describes ketones—energy molecules produced when the body lacks sufficient glucose—as particularly efficient fuel for the brain. This metabolic state can stabilize blood sugar, reduce insulin levels and decrease inflammation.

However, he cautions that not all keto diets are created equal. “People can make mistakes and it can be bad,” he said, highlighting the difference between “crappy keto” focused on processed foods and healthier versions built around whole foods, vegetables and quality fats. “For most people, it’s a tool, not a permanent lifestyle,” he added.

The same principle applies to other popular approaches. Paleo diets, featuring fruits, vegetables, lean meats, fish, eggs, nuts and seeds, can be beneficial when properly implemented. Similarly, vegan diets excluding all animal products require careful attention to nutritional adequacy.

“You can’t be a ‘chips and soda vegan,'” Hyman warned, underscoring the importance of whole food choices regardless of the overall framework.

Even Mediterranean diets, widely praised for promoting longevity and cardiovascular health, vary significantly in implementation. Hyman distinguishes between traditional Mediterranean eating patterns—rich in vegetables, olive oil, fish and legumes—and modern interpretations heavily reliant on refined bread and pasta.

“It’s a good foundation, but it’s really about personalized diets,” he noted.

Across all dietary approaches, Hyman consistently returns to one guiding principle: paying attention to individual responses. “How do you feel?” he asked. “Does your energy go up? Are your cravings down? Is your sleep better?”

He describes the body as “the smartest doctor in the room,” consistently signaling whether a particular eating pattern is beneficial or harmful. “Your biology always tells the truth,” Hyman emphasized.

Health experts recommend consulting healthcare professionals before adopting any new dietary regimen to ensure it aligns with individual needs and medical circumstances.