From today, restaurant and takeaway chains in England with more than 250 employees will have to display calorie content on food menus.
But this could pose a danger to people with eating disorders, it has been warned.
A specialist dietician said being able to eat out is a key milestone for those in recovery but calorie counts could increase anxiety.
Helen Hunt, 39, dubbed the decision “ludicrous” and said it could have a severe impact on mental health.
Ms Hunt spent six months having treatment when her anorexia was at its worst three years ago, and continues to recover.
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Dominic Lipinski
Health Secretary Sajid Javid
UK Parliament/Jessica Taylor
She said: "I had got to a stage where I was alright about going for a meal – going out to a restaurant is meant to be a sociable occasion.
"But now I feel like I'm going to be looking over my shoulder."
Ms Hunt added to the BBC: "Anorexia is one of the most deadly mental health illnesses.
"I don't understand why the Government has said: ‘Let's traumatise people who are suffering from an eating disorder.’
"I don't think they have really thought of the danger and the bigger picture."
Dietician Beth Gripton, from West Yorkshire Adult Eating Disorders Service, said labelling calories could trigger a relapse.
She added: “Getting patients to the point where they felt comfortable eating out was an important part of recovery.
"If they're then faced with the numbers it will add to that challenge, add to the guilt and shame they already experience around eating and be dangerous to someone who is trying to recover.”
The Department of Health and Social Care said obesity was one of the biggest health issues in the country and it was taking "decisive action to help people live longer lives".
A statement reads: "Displaying calorie information on menus can help people consume fewer calories when eating out or getting a takeaway, as well as encouraging businesses to provide lower-calorie options for their customers.
“The regulations allow businesses to provide menus without calorie information at the request of the customer, for those who might find viewing this difficult."