Soda and food manufacturers often fund studies on nutrition, as well as pay doctors, so not all scientific-sounding studies or experts may be objective. David Ludwig, a professor at Harvard Medical School. “You can eat a bowl of corn flakes with no added sugar, or you can eat a bowl or sugar with no added corn flakes they might taste different but below the neck, they’re metabolically the same,” says. White bread, white rice, potatoes and cereals turn into sugar in your body.