Second Opinion: Physical activity guidelines need to be more realistic
Despite the huge portionsof food consumed pre-1845 – men eating 50 portions of potatoes every day – very few people were overweight or obese. Photograph: Getty Images
The National Irish Famine Museum in Strokestown Park, Co Roscommon, has several interlinked rooms containing photographs, artefacts and display panels about land ownership before 1845 and why the Irish became so dependent on potatoes.
One of the panels about Ireland’s dietary habits in the 19th century caught my eye. Before the famine, Irish people, even labourers, were “among the best nourished, most physically robust, and tallest in Europe”.
Obesity was not a public health problem. Irish people ate mostly potatoes and drank buttermilk with scant rations of eggs, porridge, herrings, brown bread, odd bits of bacon, and lard or butter.
Male labourers ate 6.5kg of potatoes every day, women and teenagers 5.1kg, and children 2.2kg. This was a perfectly balanced diet, supplying the right amounts of protein, carbohydrates, fats, fibre, minerals and vitamins necessary for good health.
In pre-famine Ireland men were consuming 5,500 calories a day, women and teenagers more than 4,000 and children almost 2,000.
These amounts are well in excess of the number of daily calories now recommended by the Food Safety Authority of Ireland (FSAI): 2,400 for men and teenagers; 2,000 for women; and 1,400 for children.
Despite the huge portions of food consumed pre-1845 – men eating 50 portions of potatoes every day – very few people were overweight or obese. What was different about pre-famine lifestyles? How has Ireland ended up being the second fattest nation in the EU with 61 per cent of the population overweight or obese?
First, in the 19th and early-to-mid 20th century, poor and working class Irish people were very physically active, burning between 4,000 and 6,000 calories a day on manual labour such as farming, digging ditches, labouring and vigorous housework. Almost everyone walked and cycled everywhere. But that is not the whole story.
Being overweight or obese did not appear as public health problems until the 1970s, after which obesity rates rose rapidly, coinciding with several major lifestyle changes.
Almost all families bought a television and household appliances to make housework easy; highly processed convenience foods became widely available and, these, instead of being occasional treats, began to substitute for home-cooked natural food; people had more leisure time to sit around; and they began to drive everywhere.
Food processing is not necessarily a negative development and humans have been transforming raw ingredients, by cooking, salting, drying and fermenting, for thousands of years. It wasn’t until about the 1970s that food processing began to have more negative than positive consequences.
Food manufacturers started adding huge amounts of unnecessary sugar, salt and fat, thus rendering the raw ingredients into energy-dense, nutrient-poor food products.
Low-fat, low-calorie foods became available in the 1990s in response to growing obesity levels. This exacerbated the problem as people thought they had carte blanche to eat as much of these as they wanted.
Within 20 or 30 years physical activity had been engineered out of daily life and convenience foods were providing, weight for weight, three times the calories of natural foods.
Unfortunately, appetites did not adapt quickly enough and remained at hungry 19th century levels. Daily calorie allowances recommended by the FSAI are too generous for 21st century physical activity levels.
An average 11-stone adult who spends seven hours sleeping, two hours commuting by car, eight hours at the office, and four hours watching TV will burn only 1,900 calories a day.
Even if they walk the recommended 30 minutes, five days a week, they will gain two stone within three years. This weight will be maintained by yoyo dieting for the rest of their lives.
The facts are simple, the conclusion inescapable. Most people know if they eat too much they will put on weight. What they may not know is that the gap between calories eaten by the average adult or child and energy expended is as wide as it actually is.
It takes three hours of brisk walking to burn off a quarter-pound bacon burger and 13 hours of brisk walking to burn off a 12in pepperoni pizza.
An article in the August 2013 issue of Scientific American, Why Exercise Works Magic, concludes that “regular prolonged movement should be built into everyone’s daily habits and physical environment”. Even walking for an hour a day is not enough to achieve and maintain a healthy weight if a person is inactive or sitting down the rest of the time.
More realistic guidelines on physical activity are urgently needed or the obesity problem will never be solved.
Dr Jacky Jones is a former HSE regional manager of health promotion