Fanatics have their dreams, wherewith they weave a paradise,” wrote Keats. Reading some of the reactions to the latest governmental foray into nutritional micro-management, one can only agree.

Far from being a “momentous day for consumers”, its effect on buying behaviour will probably be marginal. Nutritional labelling is but one of several influences on consumers, yet enthusiasts seem to view it as the key to reforming the national diet. So when the hoped-for results don’t materialise, the response is “further, faster”, like a demented jockey on a rocking horse.

A more instructive approach is emerging from the work of the Institute for Fiscal Studies (‘Brits consuming 600 fewer calories than 30 years ago’, 15 June), highlighting the longer-term changes that have occurred in food consumption and the relationship between weight and sedentary lifestyles.

“Nutritional labelling is but one of several influences”

The IFS has also noted the impact of the economic downturn on shopping patterns. Since 2007, most households have seen a decline in real incomes and a simultaneous increase in the price of their weekly shop. They have compensated for this by buying less but cheaper food, some of it high in fat and sugar, which is exactly the effect some of us predicted at the outset.

Common sense suggests these changes may be more pronounced in the areas of the UK hardest hit by the recession and where nutritional levels historically have been relatively poor. Urban Scotland is probably the most extreme example, but whether the Scottish government’s focus on satfat will bring about any change in the eating habits of its inner-urban citizens is doubtful.

The weakness in all the government-led expedients so far is their assumption that poor eating habits are wholly susceptible to supply-side solutions. Change the product on offer and you will change consumers’ habits. Food, however, isn’t like that.

Change comes slowly and sometimes not at all. Ministerial exhortation is virtually useless, except when browbeating retailers and suppliers to conform to the latest orthodoxy. “By persuading others,” wrote 18th-century satirist Junius, “we convince ourselves.”

Kevin Hawkins is an independent retail consultant