Eating half a grapefruit before each meal may help you lose weight weekly! A compound in the tangy fruit can lower insulin, a fat-storage hormone, and that can lead to weight loss. It's also a good source of protein, and because it's at least 90% water, it can fill you up so you eat less.
Oats are rich in fiber, so a serving can help you feel full throughout the day. Just 1/4 cup is all you need, oats contain Resistant Starch, a healthy carb that boosts metabolism and burns fat.
A cup of black beans packs 15 grams of protein and doesn't contain any of the saturated fat found in other protein sources, such as red meat.