The rising tide of obesity and unhealthy living should not be ignored but the benefits of medicines to tackle the problem are "exaggerated", they added.
The opinion piece, written in the journal Open Heart, said other changes, such as stopping smoking, also had major benefits.
Dr Aseem Malhotra, from Frimley Park Hospital in Surrey, James DiNicolantonio, from the Saint Luke's Mid America Heart Institute in Kansas in the US, and Professor Simon Capewell, from the University of Liverpool, said research had shown many times over that simple steps could benefit health.
For example, drinking a sugary drink (150 calories) is associated with a significantly increased risk of Type 2 diabetes but a daily handful of nuts (30g of walnuts, 15g of almonds and 15g of hazelnuts) or four tablespoons of extra virgin olive oil (around 500 calories) is associated with a significantly reduced risk of heart attack and stroke.
They said estimates showed that increasing nut consumption by two servings a week could stave off 90,000 deaths from cardiovascular disease in the US alone.
"An exaggerated belief in the (modest) benefits of pharmacotherapy, aggressively reinforced by commercial vested interests, can often mislead patients and doctors, and promotes overtreatment in chronic disease management, and may even distract from and undermine the benefits of simple lifestyle interventions," they added.
They said the "continued collective failure to act is an option we cannot afford", with obesity already costing the NHS over £5 billion a year.
The costs of Type 2 diabetes in the UK exceed £20 billion and are predicted to double in the next 20 years, they added.
The researchers argued that the global burden of disease "will clearly not be prevented by medications; it will require policy interventions that make healthier diet choices easier (the 'default option').
"The most powerful and effective policies include taxation on sugary drinks, and subsidies to increase the affordability and availability of healthier foods including nuts, vegetables and fruit, in addition to controls on the marketing of junk foods and clear package labelling.
"It is time to stop counting calories, and time to instead promote good nutrition and dietary changes that can rapidly and substantially reduce cardiovascular mortality."
Victoria Taylor, senior dietitian at the British Heart Foundation, said the article reminded people to focus on their whole diet.
"But with around a quarter of adults in the UK already classed as obese and more than a third overweight, our energy intake does still need to be considered.
"Without counting the calories in every mouthful, simple swaps like choosing fruit and vegetables rather than fatty and sugary snacks, or water instead of a sugary soft drink, can help to reduce our energy consumption and enable us to reap the benefits to our waistlines as well as consuming a nutritious diet that is beneficial for our overall health."
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Dr Louis Levy, head of nutrition science at Public Health England, said calorie counting was useful for losing weight.
"We also need to eat more fruit, vegetables, oily fish and fibre and cut back on sugar, salt and saturated fat in the diet to improve our health."
Tom Sanders, professor emeritus of nutrition and dietetics at King's College London, said: "In my opinion, it is idiotic to suggest that calories don't count and then advocate a high fat diet.
"The editorial has muddled obesity prevention with cardiovascular disease prevention.
"Obesity is only prevented if energy intake is balanced by energy expenditure. Even a healthy dietary pattern can result in weight gain if too many calories are consumed.
"For example, the Mediterranean diet of Greece is often used to portray a heart-healthy diet. But Greece now has one of the highest rates of obesity in Europe."
Dr Tim Chico, consultant cardiologist from the University of Sheffield, said: "I am a little concerned that this editorial presents a false choice between calorie counting and nutritional value, when it is possible to do both.
"However I agree the main focus should be on what, rather than how much, we eat, particularly when the aim is to reduce heart disease."