Why does weight matter?
Being overweight or obese can increase the risk of developing diet-related diseases including type 2 diabetes, cardiovascular disease, certain types of cancer, stroke, high blood pressure and osteoarthritis, and reduces life expectancy by an average of 9 years. Although these diseases may be highly concerning, it’s also the health effects of being overweight which present on a daily basis, such as lack of energy, pain in joints, becoming out of breath easily and not fitting into your clothes, which are likely to get people thinking about making lifestyle changes.
How common is obesity?
Great Britain and the United States are among the 6 countries where 60% of the population are overweight or obese, along with Australia, Mexico, Egypt and South Africa. Women are more likely to be obese whereas more men are classed as overweight.
How do you know if you are overweight?
You can check your body mass index (
BMI), a simple measure to identify people carrying excess fat. People with a BMI of above 25 are considered overweight and above 30 classed as obese. Certain ethnic groups may be at risk of carrying excess fat at lower cut off points. How bodily fat is distributed is also important because carrying fat across the abdomen is more harmful than fat stored on the bottom and hips. Calculate your waist to hip ratio by dividing your waist circumference (approximately 1 cm above your belly button) by your hip measurement (measure at the widest part of your buttocks). A ratio of above 0.85 in women and 1.00 in men is associated with greater health risk.
Causes of weight gain?
There are many causes contributing to the current global obesity crisis, many of which are a result of modern living. Some of the key factors that contribute to weight gain are:
Energy in vs. energy out: people are getting fatter because they are consuming more energy from food and drinks than they are expending through metabolism and daily activities. Therefore both poor dietary choices and a lack of physical activity associated with modern living are problematic.
Nutrient balance: the balance of specific nutrients may have different effects on metabolism, rate of weight loss, meal satiety and diet compliance, which go beyond the benefits of reducing calories.
Metabolism: people with a lower metabolic rate (the amount of energy your body uses to carry out normal functions) are more prone to weight gain. Metabolic rate can vary significantly depending on the amount of body fat vs. lean muscle, age, gender and size of a person.
Genetics: many studies have shown that our genes and nervous system play fundamental roles in energy and blood sugar balance which can influence body weight. Twins and adoption studies have shown that genes play an important role in explaining why some people gain more weight than others when exposed to an obesity-promoting environment.
Environment: high availability of high fat- and sugar-containing convenience foods has inevitably led to people making poor dietary choices and exceeding their required energy intakes. Unhealthy food habits and low activity levels are also passed on through families.
Appetite: our bodies have many controls in place to balance energy intake, however, rising obesity levels suggest that our food intake may be overridden perhaps as a result of modern living or by changes in brain processing.
Sedentary behaviour in combination with consumption of high energy density foods, large portion sizes and low activity levels appear to be contributing to poor appetite control. Dieting may also trigger the starvation response in the brain’s hunger, satiety and rewards region. Obese individuals may experience an inappropriately low reward response that increases the desire to eat more food.
Gut bacteria: the gut bacteria of obese people are different to those of normal weight. It is thought our gut bacteria may influence the amount of calories absorbed from food, promote fat storage, trigger inflammation and impair blood sugar control.
How can you prevent obesity, limit further weight gain and loose weight?
Dietary trends, which may prevent obesity and promote weight loss include (1):
- Calorie restriction
- Low-fat diet
- Low carbohydrates
- Low glycaemic index
- Low-energy dense foods (e.g. wholegrain cereals, high fibre, non-starchy vegetables).
- Reduced intake of sugary drinks and fast food.
There is much controversy over which dietary strategies achieve effective weight loss results and perhaps more importantly, maintain the loss long term. This is because diets inevitably tail off and unhelpful dietary habits return along with the excess calories, which result in a ‘rebound’ weight gain. This suggests emphasis should be on re-education to make long-term lifestyle changes. The balance of certain nutritional factors e.g. low glycaemic index, protein, fat and carbohydrate, may produce different metabolic results for example variations in weight loss, fat loss, muscle mass, satiety levels, appetite control, blood sugar control, blood pressure and measures of inflammation (2). Therefore rather than a ‘one size fits all’ diet, a personalised approach which considers a patients’ current eating habits, dieting history, medical history, health and physical activity levels could be used to consider the best approach to weight loss on an individual basis (2).
Here are some general guidelines to help manage weight:
- Get expert advice combining nutrition, psychological and exercise support
- Follow regular eating patterns, e.g. 3 balanced meals at similar times each day
- Eat breakfast
- Have periods of not eating between meals, avoid grazing
- Be aware of portion sizes
- Include a portion of protein with 2 or 3 of your daily meals
- Avoid eating large meals and snacking late at night
- Eat at least 5 types of non-starchy vegetables and fruit per day.
- Choose lean cuts of meat and fish instead of processed versions
- Try to eliminate sugary drinks and processed food.
- Reduce alcohol intake
- Take part in moderate physical activities for at least 30 minutes a day
- Spend less time sitting down
- Don’t crash diet
- Don’t return to previous poor eating habits
1. World Cancer Research Fund / American Institute for Cancer Research, (2007). Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, DC: AICR
2. Abete, I., Astrup, A.J., Alfredo Martinez, J., Thorsdottir, I., Zulet, M., (2010). Obesity and the metabolic syndrome: a role of different dietary macronutrients distribution patterns and specific nutritional components and weight loss and maintenance. Nutrition Reviews. 68 (4) 214-231.