Boris Johnson is a shining example of how to get "fit and svelte" without the assistance of the "nanny state", key ally Matt Hancock has said.
The Health Secretary expressed support for the Tory leadership frontrunner's pledge to review so-called sin taxes, including the sugar tax tackling childhood obesity.
Mr Hancock, who is vying for a potential role as chancellor, gave his backing despite being prepared to recommend the extension of the tax to milkshakes.
Defending the review of the sugar levy introduced in April last year, Mr Hancock held up Mr Johnson as a "very good example" of using exercise to shift weight.
"I strongly support having an evidence-based review into how these taxes are working," he told Sky News.
"Of course there's the tax, but there's more ways we can make sure that we tackle obesity.
"And Boris himself is a great example of how we can all get fit and svelte without the need of the nanny state by getting on and doing more exercise and cycling to work."
Mr Johnson has discussed his fight for fitness, writing in December that he had found out he was "carting around 16-and-a-half stone" during a doctor's visit.
But he has since lost weight, saying he shifted "12 pounds in two weeks".
"I have not only laid off the Mars Bars; I have axed the cheese," he wrote in the Spectator magazine.
"I breakfast like some Georgian hermit on porridge with a luxury sprinkling of nuts. At drinks parties I guzzle water and marvel at the Pinteresque slowness with which we come to the point."
He is also regularly photographed out running.
"Is it working? You bet it is," Mr Johnson concluded.
Some attribute the former foreign secretary's slimming and tidier haircut to the guidance of Carrie Symonds, Mr Johnson's partner, who previously worked as the Tories' communication director.
Mr Hancock's defence came amid heavy criticism of Mr Johnson's proposal not to introduce new sin taxes or increase current levels unless a review concludes they are effective and do not unfairly hit those on low incomes.
The sugar tax on soft drinks has been celebrated by the Treasury for shrinking the amount of sugar in the national diet by 45 million kg a year and for raising millions in sports funding.