Monitoring your progress by checking your weight regularly and measuring your waist can help to keep you motivated. You may prefer to measure success by how you feel or by the way your clothes fit instead. It's up to you.
Remember that weight on the scales only measures your total body weight, not your body composition. Many gyms and leisure centres offer a body fat measurement service, and this can be a good indicator of fat loss over time. Alternatively you can buy your own body fat monitor in many high street shops.
Measuring your waist is a great way of monitoring your progress when you follow both a healthy eating and physical activity programme. Record your waist measurement about once a week and keep a record on your chart.