This article describes a capsule that swells to fill the stomach.
Gelesis, a start-up in Boston, is testing a capsule that would be swallowed before meals. The capsule contains particles that swell to hundreds of times their size in the stomach by absorbing water, then eventually shrink and are excreted. In a demonstration, a spoonful of the particles was put into a glass of water. A few minutes later, the glass was filled with a heavy slush.
One big challenge for this idea is that someone anticipating a delicious feast might simply skip the pill.
Instead, I eat 1/2 – 1 lbs of green veggies with every lunch and dinner – a low calorie, high nutrient way to feel full!