Everyone knows a "healthy" diet and exercise can help people lose weight and get fit. But experts disagree as to what exactly a healthy diet is! According to Business Insider, it may be little, day-to-day decisions that keeps excess weight stubbornly clinging on for dear life. One is the choice to not drink enough water. Dehydration slows weight loss and drives hunger. Second is to eat too many "healthy" foods, like avocados and nuts.