"Obesity costs the UK £54 billion each year in lost earnings and profit, and about 10 percent of the national health budget in treating related disease," ShareAction added in its statement.
Some investors have been calling for Tesco, which has 27% of the UK's grocery market, to sell more healthy food, saying it was lagging rivals in its efforts to encourage healthy eating and combat obesity in the country.
Tesco said on Friday its 65% healthy products sales target would represent a jump from the current level of 58% and it would use the government's nutrient profiling model to define those products.
Britain's biggest grocery retailer announced the move after law firm Leigh Day said Sunday it had initiated legal action against UK firm Camellia, whose subsidiary runs the site.