A cardiologist has issued a stark warning over a widely followed high-protein diet, cautioning that a common error could seriously compromise heart health. The 'keto', or ketogenic, diet is a high-fat, low-carbohydrate, protein-rich eating plan designed to alter the way the body powers itself.

When the body is deprived of carbohydrates as a source of energy, it enters a metabolic state known as 'ketosis'. However, a leading cardiologist has warned that the manner in which many followers approach the diet is placing their cardiovascular health in serious jeopardy.

Dr Francesco Lo Monaco, a private cardiologist based in London and founder of the National Heart Clinic, said: "The ketogenic diet has gained mass popularity as a weight-loss plan, but many fail to realise the associated risks. The diet's foundations in being high-fat can raise levels of LDL or 'bad' cholesterol, meaning it's not suitable for people who already have issues.

"Even for those with average cholesterol levels, increasing LDL can put a strain on any heart. But a common mistake is adopting this diet for too long.

"Keto is an extreme diet which should only be done short-term. While focusing on meat and cutting carbs, dieters are restricting the body from other key nutrients, which is not suitable long-term."

He further noted that the variety of fats consumed while following the keto diet also plays a considerable role in determining the level of cardiovascular risk. "People often assume all fats are equal, but that's not the case," Dr Lo Monaco said.

"A diet high in saturated fats from processed meats, butter and cheese can increase inflammation and contribute to plaque build-up in the arteries.

"In contrast, healthier fats - such as those found in olive oil, nuts, seeds and oily fish - are far more beneficial and should be prioritised if someone does choose to follow a low-carb plan."

Dr Lo Monaco, who is also the author of Heart Saviour, emphasised that while some individuals may experience rapid weight loss on the keto diet, this is frequently difficult to sustain and can trigger a cycle of fluctuating weight.

He said: "Short-term results can be motivating, but sustainability is key when it comes to both weight management and heart health. Many people regain the weight once they reintroduce carbohydrates, which can be frustrating and counterproductive."

Rather than following such restrictive regimes, he advocates for more balanced, evidence-backed strategies that promote long-term health and wellbeing.

"The Mediterranean diet is one of the best options for heart health. It includes plenty of vegetables, fruits, legumes and healthy fats, alongside moderate amounts of fish and lean protein. It's not restrictive, and it's far easier to maintain."