In my opinion, someone can look 'fat', yet have a healthier body than the slim ones. I think the primary determinants of having a fit healthy body is our lifestyle. Whether we eat healthy, nutritious foods and exercise often.
Someone can eat healthy and partake of regular exercise and still look obese and someone else may shun good food and exercise and look slim. We have been monstrously deceived.
I think someone can be pretty healthy if they are a bit overweight, but obese (in actual fat percentage) is unlikely to be healthy. Even the sports people who are obese for their sport, end up having troubles later because of it.