It is a combination of things.
Excess weight increases insulin resistance - which makes it easier to store energy as fat deposits (insulin resistance makes it more likely that energy gets put in fat cells than in muscle cells), and harder to lose those fat deposits. So being fat is a kind of self-fulfilling prophesy, the fatter you are, the fatter you get, and the harder it is to lose.
A simplified version of the process is that when we eat carbs, the glucose release circulates in the bloodstream until it can get into the muscles, organs and fat deposits to be used by the cells. When we have insulin resistance, the muscles resist harder than the fat cells. So the energy gets stored as fat, while the muscles go hungry. So they send messages to the brain asking for more food. Fat people (particularly obese people) end up getting fatter while their muscles and organs continually scream at them for more food, because they never get enough.
This means that reducing insulin resistance helps with weight loss - and the lower your insulin resistance, the easier it is to lose weight.
There are several ways of overcoming insulin resistance:
Exercise - this over rides the muscles insulin resistance, so the energy actually gets to the muscles
Drugs - metformin helps some people
Diet - any diet that reduces the amount of free floating glucose in the blood will mean that less insulin is produced, and less is needed. Once the body's cells are no longer constantly bathed in large amounts of insulin, they get less insulin resistant, and can react more 'normally'. So energy can get where it is needed.
So any diet that reduces glucose, will help reduce insulin resistance, which will then mean less fat storage and more energy usage by the muscles.
Basically,
@netter I would suggest concentrating on reducing your bg levels further (cutting carbs) to restart your weight loss. We all have a different level of carb intake where this happens. With me it is less than 20g carbs a day. Others it may be much more.