How can I gain weight in 7 days effectively and safely?

To gain weight effectively and safely in 7 days, focus on consuming more calories than you burn through a combination of nutrient-dense foods like lean proteins, healthy fats, and complex carbohydrates. Incorporate strength training exercises to build muscle mass, and ensure you are getting enough rest and hydration to support your body's growth. It's important to consult with a healthcare provider or nutritionist before making significant changes to your diet or exercise routine.