When it comes to dieting most people focus on calorie restriction. The understanding is that to successfully lose unwanted weight, one must ensure that more calories are burnt than consumed. Therefore most weight loss protocols suggest exercise alongside dietary changes. From a dietary point of view, the general consensus is to avoid high calorie edibles such as sweets, cakes and biscuits, but what about the essential nutrients such as fats and oils? Most people I speak to believe that fats should be the first thing to avoid when on a diet. That includes olive oil, avocados, nuts and seeds.
The dieting industry is gaining more support as global obesity increasingly makes the headlines. Worldwide obesity has nearly doubled since 1980 and recent figures suggest that at least 2.8 million people are dying each year due to being overweight (WHO 2013). Obesity related illnesses are on the rise and it is stated that the economic burden of obesity worldwide is such that medical costs for obese individuals are approximately 30% greater than those of average weight patients (Withrow 2010). Obesity is closely linked with diabetes and the World Health Organization states that overall direct health care costs of diabetes range from 2.5% to 15% of the annual health care budgets (WHO 2013).
Most adults, overweight or not, fear dietary fat. This aversion is completely justified when speaking of fried foods high in saturated fat, which health organizations such as the British Heart Foundation suggests ‘cutting right down on’. But when it comes to essential fatty acids, health organizations across the globe are promoting the regular inclusion of monounsaturated fats (olive oil, almonds, unsalted cashew nuts and avocado) and polyunsaturated fats (vegetable oil, walnuts and sunflower seeds). The regular intake of adequate levels of omega-3 fats, found in oily fish (tuna, salmon, mackerel, and sardines), is furthermore actively promoted by scientists such as Dr Alex Richardson, at Oxford University, who specializes in child behaviour and nutrition. Her research has highlighted the link between inadequate unsaturated fat intake and behavioural concerns found across the learning disability spectrum.
Oils and fats are the most compact dietary energy source but equally play a vital role in body metabolism. Foods high in saturated fat include dairy (butter, cream, milk, and cheese), meat (liver, lamb, beef, and pork), and some vegetable oils (coconut oil, palm kernel oil, palm oil, hard margarine, and lard) (Fox & Cameron 1995). Restriction of these foods is well advised when addressing calorie intake to address weight concerns. However, if one is to avoid all fat containing food and replace it with low fat options are you still gaining nutritional benefit? The WHO states that all individuals should regularly include unsaturated fats and nuts in the diet and balance energy intake with at least 30 minutes of daily exercise (a minimum of 150 minutes per week for adults). The intake of good fats therefore should be balanced with adequate daily activity.
When avoiding fat due to its calorie content the alternative is to consume increased amounts of carbohydrates. However, carbohydrates convert to glucose (sugar) in the body as a form of available fuel, and this alternative can still result in undesired weight gain when energy expenditure is not addressed. A healthier alternative to traditional sticky toffee pudding on the BBC Good Food website, shows that a low fat, ‘guilt-free’ version supplies 339 kCal per serving. Compare that to a cup (150g) of raw avocado, which supplies 240 kCal. The carbohydrate content of the pudding is 73g (of which 25g is sugar) and for and avocado only 13g. When considering dietary fibre, the avocado provides 10g and the dessert 2g. Given that the government guideline for dietary fibre is 18g per day, and that the link between dietary fibre and the prevention of colon cancer is receiving much attention of late, cutting out avocado whilst keeping the “healthy” pudding is clearly an unwise choice.
How does a low fat option nutritionally compare to regular choices? Let us look at plain yogurt. When comparing 1 cup (245g) of whole milk yogurt with low fat we note that the calorie content rises from 149kcal to 154kcal and that the fat content is reduced from 8g to 4g. However, the carbohydrate content increases from 11g to 17g per serving.
Calcium is a very important micronutrient in a diet for a myriad of functions, including good bone health. What would be the consequence of choosing a low-fat, low calorie version of cheddar cheese with respect to calcium content? A slice (28g) of regular cheddar compared to a low-fat option results in the calcium content being reduced from 20% to 12%. This comparison shows the importance of considering both macronutrient content (protein, carbohydrate and fat) and micronutrient (vitamin and mineral) status when focusing on calorie restriction. Just because you are reducing the ‘bad’ fats or the excess calories does not mean that you benefit completely from your new choices when viewing it from an overall nutrient intake.
It is no mean feat to stay slim and healthy when confronted with a plethora of food choices and often, conflicting information about their possible health benefits. Fat has been vilified and calorie restriction has been sold as the answer to our noticeable increasing population girth. The undisputed truth is that food falls into two groups, essential and non-essential. A low fat, sugar free biscuit, cake, dessert or beverage contain fewer calories than its counterpart, but remains a non-essential food. Unsaturated fats such as olive oil, nuts, seeds, and oily fish may be calorific but form part of essential foods and should be included in your daily diet for long-term health. Carefully consider what you put on your plate and how your lifestyle compliments your choices, rather than believe that a ‘guilt-free’ dessert will not find a way to linger on your hips.
BBC Good Food Website (2013), http://www.bbcgoodfood.com/recipes/3070/guiltfree-sticky-toffee-puds, accessed on 16 July 2013
British Heart Foundation (2013), http://www.bhf.org.uk/heart-health/preventing-heart-disease/healthy-eating.aspx, accessed on 16 July 2013
Department of health (1999) ‘Dietary Reference Values for Food Energy and Nutrients for the United Kingdom’. The Stationery Office, London.
Fox, B.A. & Cameron, A.G. (1995) ‘Food Science, Nutrition & Health’, 6th Ed, Arnold, London
Nutrition data (2013), http://nutritiondata.self.com/, accessed 17 July 2013
WHO (2013), http://www.who.int/mediacentre/factsheets/fs236/en/, accessed on 16 July 2013
Withrow, D. & Alter, D.A. (2011) ‘The economic burden of obesity worldwide: a systematic review of the direct costs of obesity.’ PubMed
This article was published in issue 212 of Positive Health On-Line Magazine in February 2014