A physician with whom I worked told me the same information two decades ago. Apparently, the brain believes we are getting sugar and signals the pancreas to produce more insulin. Without the actual sugar there, existing blood sugar is lowered by the insulin and we feel hungry.
Falling blood sugar is what causes us to feel hungry, whether from artificial sweeteners (diet sodas) or from consuming refined carbohydrates, which first spike the blood sugar (releasing neurotransmitters in the brain, making it addictive), then with the excess insulin produced, our blood sugar then drops rapidly, inducing extreme hunger, causing us to repeat the process daily. Besides exaggerated hunger sensations, carbohydrate addicts also experience craving and even withdrawal when we stop consuming the simple carbs (sugar, flour, rice, potatoes, corn). This, plus the extreme hunger sensation, is compelling to some and makes them obese.
Contrast this with avoidance of these simple carbs. Within about 3 days, the body undergoes a chemical, metabolic change to begin burning stored fat for energy, converting it to ketones which are then metabolized by the cells. Since many of us have excess fat stored on our bodies, we are essentially being constantly fed, as though with an I-V drip, so our blood sugar remains much more constant, our appetite is tames, and weight loss is easy… as long as we stay away from the simple carbohydrates. Green vegetables and leafy vegetables are low enough in carbohydrates and high enough in fiber (which slows their absorption), so are a good source of fiber, vitamins, minerals, and other nutrients.