1. Hot peppers
Bell peppers, Jalapenos, and cayennes don't just add flavor—thanks to a chemical called capsaicin, these veggies amp up your calorie burn too. It increases blood circulation and metabolic rate, making your body burn fat faster. These foods also provide carotenoids and twice the amount of vitamin C found in citrus fruits. Research shows that a spicy meal can increase your metabolism by up to 25 percent for three hours after you've eaten it
2. Green tea
Green tea contains epigallocatechin, which stimulates the nervous system—without elevating your heart rate. Reports suggest that people who drank green tea and exercised regularly burned more calories than those who sweated but didn't sip. Green tea contains a great number of antioxidants, help lower blood sugar level, helps to burn more fat, and reduce the signs of cellulite.
3. Citrus Fruits
Citrus fruits like oranges, grapefruits, and lemons also help to burn fat and keep your metabolism high. In addition, because of the high amount of vitamin C, citrus fruits regulate the level of insulin. Grapefruit contains naringenin, an antioxidant that helps your body use insulin more efficiently, keeping your blood sugar in check and improving calorie burn
4. Omega-3 fatty acids
Omega-3 fatty acids are primarily found in fish, but they are also present in nuts and seeds, flax, and hemp seed oil. These foods speed up your metabolism because they reduce the production of a hormone called leptin (a natural chemical that slows down your metabolism). The Omega-3 fats are in the form of DHA (Docosahexaenoic acid) which decreases your chances of putting on weight, improves brain health and fight depression. Amino acids in salmon help your body burn more calories.
5. Whole grains
The intake of grains and cereals is always recommended in a healthy diet. The secret is to choose whole grains — for example, wheat, oatmeal, rice, and corn. Whole grains have nutrients and complex carbohydrates that accelerate your metabolism by stabilizing insulin levels. They help you stave off hunger, but whole grains also take more energy to digest, so your body burns more calories when you eat them