'Light' versions of popular food brands can contain high levels of fat The group urged shoppers to check labels when they shop. In another example, Which? said that low-fat yoghurt from Tesco has more calories and sugar - but less fat - per pot than standard yoghurt from Activia. Its research also found widespread confusion among consumers over the meaning of certain words used on packaging. While shoppers believe that words such as "light" and "low fat" are interchangeable, Which? said that they have significantly different meanings. Under nutrition guidelines, products labeled as being "light," "lite" and "reduced fat" have to contain only 30 per cent less fat or saturated fat than standards products. Meanwhile "low fat" means that a product has to contain less than 3 per cent fat. However only one on six people know this, Which? found in a survey of 1,000 people. Richard Lloyd, executive director at the consumer group, warned consumers to read the labels carefully before they buy "healthy" food. "Consumers are choosing "low-fat" and "light options" believing them to be a healthier choice, but our research has found that in many cases they're just not living up to their healthy image. Our advice to consumers is to read the nutritional labels carefully," said Mr Lloyd. Consumer groups have been campaigning for supermarkets to add clearer labeling to packaging so consumers can make an informed choice about what they eat. Food manufacturers said that they make the nutritional content of their food clear on the side of the packets. United Biscuits, which makes McVitie's chocolate digestives, claimed that Which's report was misleading. A spokesman said: "While it focused on the fact that the Lights variant of the McVitie's chocolate digestive had only eight fewer calories per biscuit than the standard product, it ignored the fact that the Lights version had 30 per cent less fat. It also wrongly suggested that the fat reduction was achieved by reducing the amount of chocolate on the Light variant - this is not the case. The fat reduction has been achieved due to changes to the biscuit dough recipe. The spokesman added that its various varieties of biscuits "clearly" show nutritional information on the packs. A Tesco spokesman said: "We take seriously our responsibility to help our customers make healthy choices. Our products display clear nutritional information on the front of the packaging, and we always act in accordance with the strict rules around the use of words such as Reduced or Light. Special K said that the cereal had been developed to include the vitamins and minerals women might miss out on if they are following a calorie controlled diet.