The woman behind Sam Smith's incredible weight loss strongly advises against counting calories in order to lose weight.

Amelia Freer, a nutritional therapist and author of the book "Cook. Nourish. Glow," revealed in a recent interview that having enough sleep and a healthy eating diet that even involves calories are all needed to achieve weight loss.

According to Daily Mail, Freer said in an interview that the amount of sleep, eating patterns and a person's hormones are all big factors that can either help or sabotage a weight loss plan. The 40-year-old bestselling author said that a body's propensity to lose weight differs based on some external and internal factors.

"They're unpredictable, unique and heavily influenced by both internal and external factors, like age, hormones, quality of sleep, gut health and how active we are. Calories and diet plans, on the other hand are a one-size fits all approach," she said.

The nutritionist, who has worked with A-list stars including artists Smith and Boy George, also revealed two ways when counting calories no longer works. She said when a person is at least being active while following a diet plan of eating whole foods, then "calories don't need to be given much thought" anymore.

Freer old likewise told The Telegraph in a separate interview that she does not advise her clients to abruptly quit with their sugar intake. Keeping in mind that "big changes are hard to make; small ones are easy," Freer said she tells her clients to "go from two sugars" in their tea to one until eventually there's none.

"Eventually all these tiny tweaks will result in a low- or no-added-sugar diet, yet it will feel fairly easy. And each change will bring about a health boost that will spur you on to make the next," she told the news outlet.

The Telegraph also shared a few of Freer's tips to living a happy and healthy life on their website, which includes giving up on snacking, having happy thoughts, eating with grace and giving up on sugary drinks.

Freer's success in helping her clients achieve weight loss is evident on Smith's now-thin frame. The singer had credited the nutritionist in helping him lose weight in as little as two weeks. In fact, he took to his Instagram in March to thank Freer while posing for a photo holding her book. The singer has since been a loyal fan of Freer's books, including her first book "Eat. Nourish. Glow."