In that age range, girls are just hitting puberty. It is a period of faster growth than any other time in their lives since infancy. Limiting calories is therefore not a good idea for girls in that age group, since their bodies need extra energy in order to grow, unless they are having health problems due to weight. Making healthy dietary choices and getting plenty of exercise are good ideas. Just keep in mind - the belly fat that many girls accumulate early in puberty tends to move elsewhere in their later teens.
If you’ve got weight to lose and you want it gone fast, try swapping out your usual proteins in favor of fish. Not only is fish lower in calories than an equivalent amount of beef or chicken, a study published in Obesity reveals study subjects who added omega-3 fatty acids, like those found in fish, to their diets shed more weight and had an easier time keeping it off than those who skipped them.
The good news is that studies show that moderate- to high-intensity aerobic exercise such as running can help reduce visceral fat, even without changing your diet. Combining aerobic exercise with a healthy, low-calorie diet is even better for both overall weight loss and visceral fat loss, though exercise seems to be more effective than diet when it comes to targeting visceral fat.
The most important thing you need to do is to program yourself mentally. Don't use a scale to measure your progress. If you work out with weights, you may gain a few pounds while losing inches around the waist. Instead, use that pair of jeans that you want to fit into again, or a pair that fits you now. You'll see a slight change every few weeks, and that should give you confidence.
Most of the bacteria that dwell in your gut are pretty useful. They produce hormones, regulate your immune system, digest food, extract nutrients, control your mood, manage your appetite, and much more besides. That obese people tend to have higher numbers of Firmicutes bacteria is no coincidence – according to research published in the online journal Nature, these bacteria increase the number of calories your body absorbs from food.