There is no science to back up targeted fat loss, in fact there are studies to refute it.
Two major factors: First,
fat contained in fat cells exists as triglycerides. Muscle cells, however, cannot directly use triglycerides as fuel. It must be broken down to glycerol and free fatty acids, which then enter the bloodstream. As a result, the fat broken down to be used as fuel during prolonged exercise can come from anywhere in your body, not just the part that is being worked the most.
many of the exercises commonly associated with spot reduction do not actually burn many calories.
However, there is some science that supports a very tiny amount of spot-shaping to be possible, but it's very miniscule.
working a given muscle for 30 minutes at low to moderate intensities did increase fat cell lipolysis in blood flow.
Based on the measured changes in blood flow and lipolysis, the researchers estimate that, in 30 minutes of local exercise, an additional .6-2.1 milligrams (one milligram is one thousandth of a gram) per 100 grams of adipose tissue adjacent to contracting muscle was mobilized.
First let’s assume that you’re carrying a whopping 5 kg (11.1 pounds) of fat in a specific area.
If local exercise can mobilize 0.6-2.1 milligrams of fat per 100 grams of fat mass, that works out to:
0.6-2.1 mg/100 grams * 1000 grams/kg * 5 kg = 30-105 milligrams of fat.
Or 0.03-0.1 gram of extra fat mobilized in 30 minutes of activity.
Now, a single pound of fat (0.454 kg) contains about 400 grams of fat so our hypothetical 11.1 pounds of fat contains 4,440 grams of fat. And 30 minutes of local activity mobilized at most 0.1 gram of fat. Whoo hoo. You’ll be ripped in about 1000 years.