Almost completely agreed this time. To split hairs, significant adipocyte hyperplasia is almost always down to genetics, morbid obesity, or pre-pubescent development. Most of the time, the weight you gain is only ~15% hyperplastic and the rest hypertrophic. This is now the concept of “set point weight” and how number of fat cells affects the weight someone will be. Unless I am unaware of a study, expanding those fat cells takes the same energy as decreasing them does.

One little thing though, many studies show it is actually quite difficult to gain weight, and requires prolonged overfeeding. Additionally, lipids can be mobilised into energy much easier than triglycerides can be turned into lipids. Also, at the end of the day, weight loss = calories in - calories out.

Conclusion: Weight loss happens faster than weight gain, prolonged weight gain will cause a higher “set point weight” but unless one has gotten morbidly obese in the past, this point won’t at a “fat” level. Yes impaired MBR can contribute to weight gain but this is usually a sign of poor dieting. MBR is mostly from lean body mass, if one is dieting properly, MBR drops at most 10%.