{"id":98749,"date":"2025-08-28T13:02:10","date_gmt":"2025-08-28T13:02:10","guid":{"rendered":"https:\/\/www.newsbeep.com\/uk\/98749\/"},"modified":"2025-08-28T13:02:10","modified_gmt":"2025-08-28T13:02:10","slug":"revealed-negative-calorie-foods-that-take-more-energy-to-digest-than-they-contain-doctors-and-experts-tell-of-an-extraordinary-experiment-that-shows-the-truth","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/uk\/98749\/","title":{"rendered":"Revealed: ‘Negative-calorie’ foods that take more energy to digest than they contain. Doctors and experts tell of an extraordinary experiment that shows the truth"},"content":{"rendered":"

Negative-calorie foods are big news on social media, with influencers extolling their virtues as a fast way to lose weight<\/a>.<\/p>\n

The claim is that when we eat certain foods \u2013 mainly fruit and veg, such as celery, cucumber, lettuce, melon and grapefruit \u2013 we burn more calories digesting them than they contain.<\/p>\n

Scrolling through the huge number of posts on Instagram or TikTok<\/a>, you\u2019d be forgiven for thinking that the humble celery stick in particular is some kind of super-charged fat burner. Influencers such as Jake the Low Calorie Guy recommend snacking on celery or basing your diet mainly on similar foods to lose weight.<\/p>\n

So is eating them a clever diet trick \u2013 or just another viral myth?<\/p>\n

The \u2018negative-calorie\u2019 foods are essentially low calorie, high-water content plant foods.<\/p>\n

The theory is simple: digesting food uses energy, and some foods are so low in calories and high in fibre that your body could burn more than you consume while still leaving you feeling full.<\/p>\n

Celery, for example, has just six calories per large stalk, while half a medium cucumber contains roughly 25 calories.<\/p>\n

With numbers that low, it\u2019s tempting to imagine crunching your way to a slimmer you.<\/p>\n

\"Celery <\/p>\n

Celery has had a reputation as a ‘negative calorie’ food for a while – but is it justified?<\/p>\n

Indeed diet books have been championing celery and cucumber as low-calorie snacks for decades.<\/p>\n

So what about the science?\u00a0<\/p>\n

Professor Thomas Barber, an obesity expert and endocrinologist at University Hospitals Coventry and Warwickshire NHS Trust, has carried out experiments on this and tells the Daily Mail: \u2018We found celery was effectively a calorie-deficit food.\u2019<\/p>\n

He recalls an experiment for Channel 4\u2019s Food Unwrapped in 2016, which involved putting the show\u2019s presenter, Matt Tebbutt, into a sealed metabolic chamber that precisely records the air going in and coming out.<\/p>\n

As he explains: \u2018By analysing the oxygen and carbon dioxide levels \u2013 something called indirect calorimetry \u2013 we could then calculate his metabolic rate both before and after eating, giving us exactly how many calories eating a particular food had burnt off.\u2019<\/p>\n

\u2018This is because when we eat a meal, our metabolic rate rises for two to three hours after, as our energy expenditure goes up.<\/p>\n

\u2018This is mainly due to the liver working hard breaking down food and absorbing nutrients, and releases carbon dioxide in the process. This all requires energy. Called the thermic effect, it\u2019s why you often feel hot or sweaty after eating a big meal.\u2019<\/p>\n

The celery experiment was revealing. \u2018After getting the base-level reading of Matt\u2019s metabolic rate, we gave him 53 calories\u2019 worth of celery to eat and then measured his rate again over the next two hours,\u2019 adds Professor Barber.<\/p>\n

\"Louise \"Professor <\/p>\n

Professor Louise Dunford was dismissive of the findings of Professor Barber’s team<\/p>\n

\u2018Surprisingly, we discovered he used 72 calories to metabolise the celery meal \u2013 a difference of 19 calories and a lot more than the generally accepted 10 per cent of total calorie content rule of how much energy is used to digest most meals.<\/p>\n

\u2018So in this way, we found celery was effectively a calorie-deficit food.\u2019<\/p>\n

But Professor Barber is quick to point out that these findings don\u2019t amount to a full-blown dietary strategy. \u2018Indirect calorimetry using a metabolic chamber like this is an excellent way to assess metabolism and thermic effect of food in real time. But applying this to general dietary advice is missing the point.<\/p>\n

\u2018Yes, negative calorie fruit and veg may exist, but that\u2019s not the most interesting thing about them.\u2019<\/p>\n

He adds: \u2018I personally feel there\u2019s far too much focus on calories per se, rather than looking at good nutrition and the fact that these plant-based foods are actually very beneficial for our health.<\/p>\n

\u2018Celery contains some key vitamins and minerals (including vitamins C and K, and potassium) and is high in fibre, which is a crucial part of a healthy diet.<\/p>\n

\u2018Our over-reliance on low-fibre ultraprocessed foods means most of us eat only two thirds of what our bodies need to function well.<\/p>\n

\u2018And plant-based foods such as celery are one of the best fibre sources \u2013 especially of the type of insoluble fibre our healthy gut bacteria need to feed on, something a wealth of evidence now shows is vital for overall good health,\u2019 he explains.<\/p>\n

Other experts are more dismissive about the existence of negative-calorie foods.<\/p>\n

Dr Louise Dunford, a nutritionist and an associate professor at the University of Warwick, is unequivocal. \u2018The idea is nonsense \u2013 and has no science to back it up,\u2019 she says.<\/p>\n

\"Pink <\/p>\n

Pink grapefruit is another food said to help people lose weight due to its calorific content<\/p>\n

She also disputes the calculations for negative-calorie foods.<\/p>\n

\u2018Typical foods people pick out as being \u201cnegative calorie\u201d are celery, grapefruit, cucumber \u2013 basically anything with high water and fibre content but very low calories (14-30 calories per 100g),\u2019 Dr Dunford told the Daily Mail.<\/p>\n

\u2018But the truth is, although these foods are low in calories, they also take far less energy to digest because of their high water content and the indigestible fibre they contain, which isn\u2019t digested \u2013 it just passes through the digestive system,\u2019 she explains.<\/p>\n

\u2018It\u2019s generally accepted that the energy required to digest meals is around 10 per cent of the total calories they contain, although this can vary depending on protein levels, as protein uses more like 20-30 per cent of the energy it contains to burn it off.<\/p>\n

\u2018So celery is just a lower-calorie food not a calorie-deficit creator,\u2019 says Dr Dunford.<\/p>\n

\u2018These foods are not some magic bullet that are going to somehow remove calories from your overall intake as some people think\u2019.<\/p>\n

She is also critical of any suggestion to focus on foods considered negative calorie choices.<\/p>\n

\u2018It wouldn\u2019t be sustainable – you would be hungry all the time and miss out on other key nutrients such as protein,\u2019 Dr Dunford points out, adding that you could also end up suffering from diarrhoea or excess gas in the short term if you weren\u2019t used to eating a lot of these foods.<\/p>\n

Yet even if fruit and veg won\u2019t magically blast away excess calories, \u2018that\u2019s not to say they\u2019re not healthy foods that can help with weight loss\u2019, she continues.<\/p>\n

\u2018For example, swapping a portion of chips for a side salad is a very sound weight management strategy.<\/p>\n

\u2018Choosing carrot sticks instead of crisps reduces calories while also boosting fibre and hydration. And having grapefruit or berries for dessert is always going to better for your waistline than cake,\u2019 says Dr Dunford.<\/p>\n

Professor Barber echoes this \u2013 what makes these foods truly valuable ultimately isn\u2019t their \u2018negative-calorie\u2019 content \u2013 \u2018it\u2019s their high nutrient content and the role they play in supporting gut health\u2019, he says.<\/p>\n

\u2018So the real story isn\u2019t calories at all \u2013 it\u2019s the nutritional power of plant-based foods.\u2019<\/p>\n","protected":false},"excerpt":{"rendered":"Negative-calorie foods are big news on social media, with influencers extolling their virtues as a fast way to…\n","protected":false},"author":2,"featured_media":98750,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[45],"tags":[97,102,103,6636,617,56,54,55],"class_list":{"0":"post-98749","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-nutrition","8":"tag-dailymail","9":"tag-health","10":"tag-instagram","11":"tag-nutrition","12":"tag-tiktok","13":"tag-uk","14":"tag-united-kingdom","15":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/98749","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=98749"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/98749\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/98750"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=98749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=98749"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=98749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}