All foods - including fast food and snacks - should carry clear warnings about their calorie content, MPs suggested on Thursday.
Advertising influences children's eating habits, the FSA has found
Top executives from McDonalds, Cadbury Schweppes, PepsiCo UK and Kelloggs faced questions from the House of Commons Health Select Committee.
Obesity levels are soaring in the UK, but the firms said they did not believe that this was their fault.
The Food Standards Agency has described the problem as a "ticking timebomb".
Consumers should know how much exercise it would take to burn off a meal or sweet
before eating it, David Hinchliffe said.
A McDonald's cheeseburger with fries and a shake equated to a nine mile walk, he claimed.
He said: "At the moment calorie content does not mean a great deal to people."
"Perhaps the message is not sufficiently blunt."
He agreed that any system would have to be universal, not just covering sweets and fast food.
At the moment packaged foods such as chocolate, crisps and snacks does carry details of its calorie content in small print somewhere on the packaging, but burger packaging does not, although the information is available in restaurants.
Julian Hilton-Johnson, vice-president of McDonalds Restaurants Ltd, said people should be clearly told what they were eating.
However, he said that most people visited his restaurants only two or three times a month - meaning the vast majority of their excess calories, if they were obese, came from elsewhere.
He rejected the idea that the firm was either encouraging children to eat too many burgers by selling "Happy Meals" with a succession of toys to collect - or that it was harming health by pushing larger portions.
He said: "A Big Mac has 490 calories - if you were to buy a cheese and tomato sandwich from a high street store, it might have 600 or 650."
He said it was the responsibility of parents to ensure that their children had a healthy, balanced diet - but called on the government to coordinate efforts to get the message across.
"It would be logical for the government to act as a leader and coordinate this. It is the parents who have to take responsibility for what their children eat.
"I don't think it's for us to presume to tell our customers what they should not be eating."
The inquiry comes after McDonald's was banned on Wednesday from repeating a "misleading" advert for its fries.
The advert said that after selecting certain potatoes "we peel them, slice them, fry them and that's it".
But complainants to the Advertising Standards Agency said parts of the process had been omitted, such as part-frying, freezing and adding salt and a dextrose sugar solution.
Martin Paterson, from the Food and Drink Federation which represents the companies attending the meeting, says the food industry is already doing things to help address the problem of obesity.
"Every single day new products with lower fat, lower sugar and lower salt are coming out and the idea is to provide people with choice.
"But we want to back that up with education and information for consumers so their choice can be an informed one."