Final answer:
Marvin needs to create a caloric deficit by consuming fewer calories than his body burns. Following a low-calorie diet and increasing physical activity, along with behavioral interventions such as monitoring food portions and starting a gradual exercise routine, can help him lose weight healthily.
Step-by-step explanation:
Marvin wants to lose 25lbs. In order to reach his goal, he needs to create a caloric deficit. This means consuming fewer calories than his body burns. According to the principles of thermochemistry, a deficit of about 3,500 calories is required to lose 1 lb of weight. By adhering to a low-calorie, low-fat diet and engaging in physical activity, he can increase the energy his body uses.
Behavioral interventions, such as monitoring food portions, avoiding an all-or-nothing attitude towards exercise, and being kind to oneself can support weight loss. It's important for Marvin to start slowly with exercise and gradually increase the duration and intensity to at least 30 minutes a day, five days a week.
Ensuring a balanced approach combining diet and exercise will help him not only achieve weight loss but also maintain it. The objective is to establish a lifestyle change rather than opting for quick fixes. Following these guidelines can lead to a steady and healthy weight loss of one to two pounds a week.