Based on research conducted by the University of California, juice in pomegranates ranked as the fruit juice with the most antioxidants. Among some of the antioxidants in pomegranates are polyphenols, also called catechins. Catechins increase fat-burning and speed up the body's metabolism. Additionally, catechins exhibit appetite inhibition and stops arterial build-up of lipids. According to MedlinePlus, pomegranates have been used in experimental weight loss treatment of obese adults.
Watermelon is over 90 percent water, helping to release toxins and fat in the body, as reported by North Carolina State University. Among all other fruits and vegetables, watermelon contains the most lycopene. Lycopene prevents heart disease by halting plaque and lipid build-up. L-citrulline, also found in watermelons, acts in conjunction with other amino acids to lower blood sugar and flush fats from the body. When blood-sugar levels are consistently lower, insulin levels do not spike. Spiking insulin causes storage of belly fat.
Sweet potatoes are high in fiber and vitamins that can boost your metabolism by helping your body get rid of waste efficiently, while also supporting your cells as they convert food to energy. The American Diabetes Association recommends eating sweet potatoes when trying to lose weight. Sweet potatoes, along with other orange vegetables such as carrots and pumpkin, can help you achieve a healthy metabolism and weight.