Track your horse's progress by using a weight tape. The tapes are remarkably accurate and provide a good way to gauge weight loss. When the horse's weight plateaus, gradually cut back its ration again. Step up the horse's exercise regimen. Gradually build time and intensity as the horse's fitness improves.
Some horses are natural pasture potatoes.
Ride, longe, drive or work the horse on a treadmill rather than rely on free choice exercise. Provide plenty of clean, fresh water so the horse's digestive and other systems function as efficiently as possible and rid the body of metabolic and other wastes. Select feeds that provide plenty of high quality fiber but are low in total energy. Measure feeds by weight rather than volume to determine appropriate rations. Select feeds that are lower in fat since fat is an energy-dense nutrient source Switch or reduce the amount of alfalfa hay fed.