Obesity and exercise

• weight reduction is best achieved by a combination of dietary change and increased physical activity
• increased physical activity carries significant benefits for cardiovascular performance, blood pressure, blood lipids and glucose metabolism
• to achieve long-term increases in physical activity, these will need to be incorporated into everyday life, e.g cycling or brisk walking - a suitable duration would be 20-30 minutes per day
• increased physical activity results in only modest changes in weight, averaging 0.5 to 1kg reduction each month (1) - walking an additional 2,000 steps per day increases energy expenditure by 100 calories
  • increased physical activity should therefore be combined with calorie-restricted diet in order to achieve significant weight loss
  • physical activity tends to become easier with time - this promotes a virtuous cycle in which physical activity increases further as the activity becomes easier to undertake
  • people who persist with regular physical activity are more likely to maintain their weight loss
• NICE have stated
  • with respect to exercise in adults (2):
    • adults should be encouraged to increase their physical activity even if they do not lose weight as a result, because of the other health benefits physical activity can bring, such as reduced risk of type 2 diabetes and cardiovascular disease. Adults should be encouraged to do at least 30 minutes of at least moderate-intensity physical activity on 5 or more days a week. The activity can be in one session or several lasting 10 minutes or more
    • to prevent obesity, most people should be advised they may need to do 45-60 minutes of moderate-intensity activity a day, particularly if they do not reduce their energy intake. People who have been obese and have lost weight should be advised they may need to do 60-90 minutes of activity a day to avoid regaining weight
    • weight loss should be a maximum of 0.5-1 kg/week
    • management of obesity
      • only consider drug treatment for obesity if dietary, psychological and exercise interventions have been tried and failed
      • consider surgery for people with severe obesity if BMI 40 or more or 35-40 with significant disease, all non-surgical interventions should have been tried for at least 6 months
      • consider surgery as a first line option for adults with a BMI of more than 50 kg/m2
    • adults should be encouraged to build up to the recommended levels for weight maintenance, using a managed approach with agreed goals. Recommended types of physical activity include:
      • activities that can be incorporated into everyday life, such as brisk walking, gardening or cycling
      • supervised exercise programmes
      • other activities, such as swimming, aiming to walk a certain number of steps each day, or stair climbing
      • any activity should take into account the person's current physical fitness and ability
      • people should also be encouraged to reduce the amount of time they spend inactive, such as watching television or using a computer
        
        
    • with respect to children (2):
      • children should be encouraged to do at least 60 minutes of at least moderate activity each day. The activity can be in one session or several lasting 10 minutes or more
      • children who are already overweight may need to do more than 60 minutes' activity
      • children should be encouraged to reduce sedentary behaviours, such as sitting watching television, using a computer or playing video games
      • only consider drug treatment for obesity if dietary, psychological and exercise interventions have been tried and failed for at least 6 months
      • if drug treatment is considered appropriate this should be commenced by a specialist as part of a multi-disciplinary team
      • surgery should only be considered in exceptional circumstances
      • the World Health Organisation (WHO) advises that:
        • children between 5-17 years of age should be engaged in at least 60 minutes of moderate to vigorous exercise on a daily basis with the majority of this being aerobic in nature (3)
      • NHS choices suggest that children under 5 should be encouraged to be active for at least 180 minutes daily (4)
        
        
• regular physical activity has important effects on the distribution of body fat, favouring reduced adiposity
  • the redistribution of body fat associated with regular exercise reduces the risk of both coronary heart disease, the metabolic syndrome and type 2 diabetes occurring
  • other cardiovascular effects of regular physical activity include (1):
    • improved
      • cardiac contractility
      • stroke volume
      • electrical stability
      • endothelial function
      • collateral circulation
    • reduced
      • blood pressure
      • platelet aggregation
      • plasminogen activator inhibitor 1
      • plasma-fibrinogen
      • C- reactive protein
      • triglycerides
      • mortality
    • increased
      • fibrinolysis
      • HDL-cholesterol
      • lipoprotein lipase
      • insulin sensitivity

Contributors May 2012:

• Dr Alethea Beck General Practitioner, Scotland
• Dr Andrew Murray Sports and Exercise Medicine registrar, Scotland

Reference:

1. British Heart Foundation (1/2005). Factfile - Obesity: physical activity
2. NICE (November 2014). Obesity Guidance
3. World Health Organisation, Global Strategy on diet, physical activity and health
4. NHS Choices, Physical Activity Guidelines for children,