The best strategy for keeping (or getting back) a trim waistline is a 3-part approach: diet, exercise, and posture enhancement.
Carbohydrates push up blood sugar; insulin levels rise and high insulin levels cause fat storage in the abdomen. Estrogen and testosterone help keep insulin levels low so that when they begin to decline with aging (and especially menopause), the waistline starts to widen.
Avoiding excess carbs, never eating white or processed carbs, and starting the day with a breakfast of protein (such as eggs, hummus, nuts or nut butters) are simple dietary changes that can help. Trans fats (partially hydrogenated vegetable oils) also push up insulin levels causing metabolic havoc. They should be completely avoided. Plant sources of protein (seeds, nuts, legumes, nut butters, sprouts) have special insulin lowering power, enhancing the waistline.
Aerobic exercise lowers insulin levels helping to protect the waistline. Adults should undertake at least 150 minutes a week of aerobic exercise to support a healthy metabolism. Increasing skeletal muscle mass through exercise helps the body to remain sensitive to insulin levels and improves even a resting metabolism.
Core defining practices such as yoga, Pilates, or ballet help elevate and maintain the spine, counteracting gravity's pull on the waist to hip ratio. Strengthening the core can help prevent osteoporosis and disc disease, both of which can cause a shortening (and thickening) of the waistline.