The Paleo and Keto diets beloved of celebs like Kim Kardashian and Gwyneth Paltrow are the worst for your heart, a scientific study claims. But the Mediterranean, pescatarian and vegetarian diets adopted by the likes of Beyoncé, Selena Gomez and Harry Styles are far better for us.
A new report from the American Heart Association (AHA) ranked popular diets on how good or bad they are in terms of heart healthiness. The resulting rankings placed popular selective diets such as the Mediterranean, pescatarian and vegetarian diets in the top tier for heart health.
Just above these at the pinnacle of healthy heart eating are DASH diets - subscribed to by American singers Jessica Simpson and Jennifer Hudson - which include foods rich in potassium, calcium and magnesium and are designed to control blood pressure. However, extreme dieting fads such as the Keto and Paleo diets were found to be detrimental to heart health due to reduced fibre intake and a lack of limits on consuming saturated fats.
Experts say that though these diets may result in short-term weight loss they aren't sustainable in the long run but could do lasting damage. Dr Christopher Gardner, chair of the writing committee for the new scientific statement and the Rehnborg Farquhar Professor of Medicine at Stanford University in Stanford, California, explained that disinformation spread about dieting techniques on social media means we are more confused than ever before about which diets are good or bad for our health.
He said: "The number of different, popular dietary patterns has proliferated in recent years, and the amount of misinformation about them on social media has reached critical levels. The public — and even many health care professionals — may rightfully be confused about heart-healthy eating, and they may feel that they don’t have the time or the training to evaluate the different diets.
"We hope this statement serves as a tool for clinicians and the public to understand which diets promote good cardiometabolic health."
The AMA's new healthy heart statement rates how well popular dietary patterns align with its dietary guidelines for good cardiometabolic health - a group of factors that affect our metabolisms and the risk of heart and cardiovascular disease. These factors include blood glucose, cholesterol and other lipids, blood pressure and body weight.
While abnormal levels in one of these factors might increase the risk of heart disease, abnormalities in more than one factor raise these risks even more, and for potentially deadlier diseases. The AMA's dietary guidance comprises ten key features of a dietary pattern to improve cardiometabolic health; with an emphasis on limiting unhealthy fats and reducing our consumption of excess carbohydrates.
The balance the guidance encourages aims to limit the risks of health conditions like Type 2 diabetes and risk factors such as obesity, which increases the risk of cardiovascular disease. The new scientific statement - which is the first ever to analyse how closely popular dieting techniques adhere to this guidance - reviewed the defining features of long-term dietary patterns and split them into ten different categories.
These categories include DASH-style diets; Mediterranean-style diets; vegetarian and pescetarian diets; vegan diets; low and very low-fat diets; low-carb diets; Paleolithic diets and Ketogenic diets. Each diet was evaluated against nine of the ten features in the AMA's guidance for a heart-healthy eating pattern.
Defining features of the various diets were scored for how well they aligned with the guidance, with one full point for fully meeting, 0.75 points for mostly meeting and 0.5 points for partially meeting the guidance.
The resulting scores were calculated and adjusted to arrive at a rating between one and a hundred, with 100 indicating entire adherence to the AMA's dietary guidance. Experts found the reviewed diets varied widely in their scores - ranging between 31 and 100 - and grouped the diets into four tiers of heart healthiness.
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They discovered the highest-ranking heart-healthiness diets - with scores higher than 85 - were flexible and provided a broad range of healthy foods to choose from. The DASH-style (Dietary Approaches to Stop Hypertension) diets - designed to treat or limit high blood pressure - obtained a perfect score in meeting all of the AMA's guidance.
These diets tend to be low in salt, added sugar, alcohol, tropical oils and processed foods and rich in non-starchy vegetables, fruits, whole grains and legumes. Protein tends to be mostly from plant sources (such as legumes, beans or nuts), along with fish or seafood, lean poultry and meats, and low-fat or fat-free dairy products.
The Mediterranean-style diet, which limits dairy and emphasises vegetables, fruit, whole grains, legumes, nuts and seeds, fatty fish and extra virgin olive oil - and includes moderate drinking of red wine - also received a high heart rating. This type of eating helped Big Lebowski actor John Goodman, 70, lose a jaw-dropping 14 stone by following the diet which is also adhered to by Spanish actress Penélope Cruz, 48, and American actress Cameron Diaz, 50.
The Pescatarian diet - in which the sole meat you can eat is fish - also scored high in terms of heart health, and counts singers Beyoncé, 41, Harry Styles, 29, Victoria Beckham, 49, and Miley Cyrus, 30, among its followers. Similarly, the vegetarian diet - followed by the likes of Sir Paul McCartney, 80, Zendaya, 26, and Russell Brand, 47 - was included in the top tier of diets when including dairy products and eggs.
On the strength of these diets, Dr Gardner said: "If implemented as intended, the top-tier dietary patterns align best with the AMA's guidance and may be adapted to respect cultural practices, food preferences and budgets to enable people to always eat this way, for the long term."
The second tier of diets, with scores of between 75 and 85, included vegan and low-fat diets which encourage eating fruit and vegetables, grains and nuts whilst limiting alcohol consumption and food and drink with added sugar.
However, the experts acknowledged the long-term difficulties with adhering to these strict diets when eating out, and warned vegans like actors Olivia Wilde, 39, and Joaquin Phoenix, 48, as well as ex-heavyweight champion boxer David Haye, 42, that they could risk a vitamin B-12 deficiency which could cause red blood cell abnormalities leading to anaemia by following a strict vegan diet, and recommended taking supplements.
Very low-fat and low-carb diets formed the third tier of diets with scores of between 55 and 74, with some very low-fat diets being linked with the potential slow progression of fatty artery build-up. Both diets were also said to restrict food groups emphasised in the AMA's guidance.
The lowest-ranked diets, however, with scores of less than 55, were found to be the Paleolithic and very low-carb/Ketogenic diets. The bizarre Paleo diet, which has been followed by actors Matthew McConaughey, 53, and Channing Tatum, 43, is an eating plant based on foods humans might have eaten during the Paleolithic Era of around 2.5 million to 10,000 years ago.
It focuses on foods our ancestors could obtain through hunting and gathering and avoids foods which came after the agricultural revolution such as grains, legumes and dairy products.
Subscribers to the Keto diet, meanwhile, eat plenty of fat and very few carbs, so that your body enters a fat-burning mode known as ketosis. This strange dieting technique has been sampled by the Kardashian sisters, actress Halle Berry, 56, and basketball superstar LeBron James, 38.
These restrictive diets, though helpful in the short-term for losing weight, can result in a reduced fibre intake as well as being unrestrictive on saturated fats, which could increase the risks of cardiovascular disease.
'Restrictive and difficult'
On these low-ranking heart health diets, Dr Gardner said: "There really isn’t any way to follow the Tier 4 diets as intended and still be aligned with the AMA's Dietary Guidance. They are highly restrictive and difficult for most people to stick with long term.
"While there will likely be short-term benefits and substantial weight loss, it isn’t sustainable. A diet that’s effective at helping an individual maintain weight loss goals, from a practical perspective, needs to be sustainable."
Dr Gardner added that conflicting information on diets makes it difficult for us to identify which one could work for us. We often find that people don’t fully understand popular eating patterns and aren’t following them as intended," Dr Gardner said.
"When that is the case, it is challenging to determine the effect of the ‘diet as intended’ and distinguish that from the ’diet as followed.’ Two research findings that seem contradictory may merely reflect that there was high adherence in following the diet in one study and low adherence in the other."
The AMA's guidance did not take into account commercial dieting techniques such as Weight Watchers or Noom, short-term diets intended to be followed for less than 12 weeks, practices such as intermittent fasting or time-restricted eating or diets designed to manage non-cardiovascular conditions.
