The issue here is "excess carbs" are very easy to exceed consuming grains and sugar.
Carbs (especially sugar) are what most easily gets converted to adipose fat tissue on the body... unintuitively consuming dietary fat is NOT conducive to increasing body fat. Counter intuitive but true.
Consuming a high carb diet, especially if a significant portion comes from high glycemic index sources, will guarantee body fat increase.
Oils, fats, nuts should be primary components of ones diet.
Excess body fat and high carb diet eventually leads to diabetes and metabolic-syndrome, the overall systemic decrease in health and increase in risk factors for other diseases because of being overweight (specifically, over fat).
I could post study after study but for anyone else reading this, you'll have to do your own research and learn from your own experience. Try both diets.
If you've never tried low carb (and high fat.. it's important to replace carbs with fat) then you should do so and observe your energy changes and decrease in body fat. It will happen.
Here's a good collection of references:
Look at the before and afters, read the experiences.
My nutritional and fitness experience? 5 years Army Special Operations, where diet and nutrition were studied and an important component to unit readiness....and a lifetime of sports and athletics including college football. And then studying the issue quite a lot.
Read the science behind the Atkins / Keto diet. It's not complicated how our bodies store fat.