There’s been no formal research on whether or not increasing the fat content of your body will transform a flat butt into a nice curvy round butt.
Though I have a personal training background, I’m going to affirm that you do not need to have a certification in personal training or a degree in kinesiology or exercise physiology to know what the obvious is:
A flat butt cannot be made round, let alone bubble-like, by gaining fat.
This is very evident when you simply look at the behinds of women of various sizes. Go to any crowded venue and observe.
This includes locations where many of the women are overweight (Walmart) and areas where most of the women are on the thinner side or at least not what you’d call overweight (a step aerobics class).
Look at their butts. You will notice that there are thin women with well-endowed booties, and overweight—even obese—women with flat derrieres.
This reminds me of Lauri, a woman I knew in college who was obese. She had the flattest behind.
Frankly, I see this pair-up all the time: an obese woman with a very flat bootie. They obviously have an overload of fat in their bodies, but it doesn’t collect in their behind in terms of an outward direction.
Sure, there’s more fat in their butt than if they were thin, but the way that this fat is distributed, when they are overweight, does not undo the flatness; does not add much contour or roundness.
Conversely, there are many women whom you’d consider skinny who have outright bubble butts.
Don’t assume that all of these women spend hours every week doing squat exercises, either. Some of these individuals are teenagers, some even younger.
Many appear to be anything but athletic, lacking muscle tone—quite suggestive of the absence of any strength training (let alone barbell squats) in their life.
It’s just that some females are naturally blessed with a round, curvaceous derriere, while others are genetically cursed with flatness.
Adding fat via increased food intake will not change this. In fact, this is akin to thinking you can go from a bra cup size A to a C by gaining fat.
Though you’ll need a bigger bra with fat gain, your actual cup size won’t change in the literal sense. This is why you’ll see obese women who have very small breasts—small as in “flat” – and skinny women with D sizes and more.
I’m reminded of Debby, a woman who appeared to weigh close to 300 pounds, who once worked in the same office as me. She was quite flat upstairs.
We can’t assume that all thin women who are well-endowed in their chests have had implants, especially since some of them are only teenagers.
If you have a flat butt, it will not develop the round curvy shape you desire (let alone bubble out) if you gain fat by eating more.