Maintaining a healthy body weight is essential for overall well-being and preventing various health problems. It involves adopting a balanced and sustainable lifestyle that includes healthy eating habits, regular physical activity, and setting realistic goals. Among the given options, the one that is not a step to maintaining a healthy body weight is option 'C' - Intake of calories through drinking. Let's discuss why this answer is correct in detail.

Intake of calories through drinking:
- Consuming calories through beverages can contribute to weight gain and hinder efforts to maintain a healthy body weight. Many beverages, such as soft drinks, energy drinks, fruit juices, and even certain alcoholic beverages, are often high in calories and sugar.
- Liquid calories are less satiating compared to solid foods, meaning that drinking calories may not make you feel as full as eating the same number of calories in the form of solid food. This can lead to consuming more calories overall.
- Additionally, drinking excessive amounts of sugary beverages can negatively impact one's health, increasing the risk of conditions like obesity, type 2 diabetes, and cardiovascular diseases.
- Therefore, it is important to be mindful of the calories consumed through drinking and opt for healthier alternatives like water, unsweetened tea, or low-calorie beverages.

Steps to maintaining a healthy body weight:

1. Goal setting:
- Setting realistic and achievable goals is an important step in maintaining a healthy body weight. This involves determining a target weight or body fat percentage and developing a plan to reach and sustain it.
- Goals should be specific, measurable, attainable, relevant, and time-bound (SMART goals). They should also take into account individual factors such as age, gender, activity level, and any underlying medical conditions.

2. Yoga:
- Yoga is an effective form of exercise that can contribute to weight maintenance and overall well-being. It combines physical postures, breathing exercises, and meditation to promote flexibility, strength, and relaxation.
- Regular yoga practice can help improve body composition, increase metabolism, reduce stress, and enhance mindfulness around eating habits. It can also aid in building lean muscle mass, which can help in weight management.

3. Avoiding carbohydrate-rich food:
- Carbohydrates are an important macronutrient and a major source of energy for the body. However, consuming excessive amounts of refined carbohydrates (e.g., white bread, sugary snacks) can contribute to weight gain.
- Opting for complex carbohydrates such as whole grains, fruits, vegetables, and legumes can provide essential nutrients while promoting satiety and supporting weight maintenance.
- It is important to have a balanced diet that includes all essential nutrients, including carbohydrates, proteins, and healthy fats, in appropriate proportions.

In conclusion, maintaining a healthy body weight involves various steps such as goal setting, engaging in physical activities like yoga, and making mindful choices about food intake. However, consuming calories through drinking is not a step to maintaining a healthy body weight as it can lead to weight gain and have negative health consequences.