Released this month as part of Change4Life's wider Sugar Smart campaign, the app took the number one spot on both the App Store and Google Play during its first week, according to data from App Annie.
There has been such a big increase in the consumption of fizzy drinks through focused marketing, that we have turned the corner and gone into reverse, and people’s teeth are dropping out
It has since remained in the top ten most downloaded free apps on both stores, currently sitting in fifth place for iPhones and iPads, and tenth place for Android devices.
According to public health minister Jane Ellison, the app saw 800,000 downloads in its first 10 days.
The app received considerable above-the-line investment from Public Health England, which spent £5m overall on Sugar Smart.
A spokeswoman for Public Health England said: "We are delighted with how popular [the app] is with consumers and therefore the many people that are now more informed about the sugar in their shopping basket."
Ellison, speaking during a Commons debate on child obesity last week, said the app was a successful example of how the government can "empower families with information so that they can make decisions about their diet".
Childhood obesity debate grows
The government is due to publish its childhood obesity strategy, likely next month.
This could include a ban on TV ads for high-fat, sugar and salt foods (HFSS) before 9pm, docking store promotions, and a 'sugar tax' on food and drink.
While fizzy drinks makers have complained about being unfairly targeted, citing falling sugar consumption, Labour MP Geraint Davies, a former Unilever and Colgate marketer, said they represented an "easy big hit, early on".
He said: "When I was at Colgate, we thought that with the advent of fluoride we were going to see the end of tooth decay.
"However, there has been such a big increase in the consumption of fizzy drinks through focused marketing, that we have turned the corner and gone into reverse, and people’s teeth are dropping out."
This is the first time Public Health England has released an app for its annual sugar reduction campaign. Speaking to Marketing earlier this month, marketing director Sheila Mitchell said the app was intended to convey PHE's 'sugar tax' report in practical terms.
"We found when doing focus groups, when we were revealing sugar cubes as part of the campaign development, our mums really sprung up and said that was really useful information," she said. "We thought there must be a way we could do this in app form. It’s taken some time to develop the idea and ensure most key products get into the database."
The app also stemmed from an existing partnership with price comparison site Mysupermarket.com. PHE launched a sugar accumulator for the site, showing shoppers how much sugar was in their basket with each added purchase, and offering low-sugar alternatives.
The Sugar Smart app works by allowing shoppers to scan barcodes on common items. It then visualises the amount of sugar as sugar cubes.
The app can scan up 75,000 products, informed by data from the George Institute for Global Health and Mysupermarket.co.uk. The information is updated every two months.