Final answer:
The commercial weight loss program that matches the description is Weight Watchers.
Step-by-step explanation:
Weight Watchers, now known as WW, aligns with the provided description of a three-level weight loss plan. This program emphasizes a holistic approach to weight management. The initial level involves planning healthy menus and practicing portion control. The second level prioritizes physical activity, encouraging participants to incorporate exercise into their routine. The final level concentrates on behavioral modification, addressing the psychological aspects of weight loss. This comprehensive approach aims to foster sustainable lifestyle changes. With its proven effectiveness and focus on long-term behavior modification, Weight Watchers has become a widely recognized and successful commercial weight loss program, promoting healthier habits and improved well-being.