Argentine Cardiologists Warn: Popular Diets Lack Scientific Support, Pose Health Risks

The new year arrives with its familiar rituals: resolutions, fresh starts, and the sudden conviction that this time, the diet will stick. In early January, as people shake off the holiday excess, the internet fills with promises. Detox cleanses. Intermittent fasting. Keto. Each one claims to deliver rapid transformation, metabolic renewal, or the simple gift of looking better by spring. But Argentina's Cardiology Federation wanted to know what the science actually says, and what it found was a gap between promise and evidence that deserves attention.

Diego Picchio, a cardiologist and member of the federation's environmental health and cardiovascular prevention committee, led the analysis. The conclusion was measured but clear: many of these trendy approaches lack solid scientific backing, and some carry real risks—especially for people with existing heart conditions or diabetes. The federation's job was not to shame people for trying, but to separate what works from what merely sounds good.

Intermittent fasting comes in several forms. The 16-8 method concentrates eating into an eight-hour window and fasts for sixteen hours. The 5:2 approach involves eating just one modest meal on two days each week. During fasting periods, the body first burns through available glucose, then insulin levels drop and the body shifts to burning stored fat. Some research shows modest improvements in blood pressure, LDL cholesterol, and triglycerides, along with weight loss comparable to traditional calorie restriction. But here is where the federation's caution enters: a 2024 study tracking roughly 20,000 adults over more than fifteen years found that those who compressed their daily eating into eight hours or less had a 91 percent higher risk of dying from cardiovascular disease compared to those who ate across a twelve to sixteen hour window. The study, presented by the American Heart Association, found no evidence that this type of fasting extended lifespan or reduced overall mortality risk. For people with diabetes on medication, intermittent fasting can trigger dangerous drops in blood sugar. For others, it can trigger binge eating or destabilize uncontrolled heart conditions. It is not, Picchio emphasized, a one-size-fits-all solution.

The ketogenic diet takes a different path: it slashes carbohydrates to just 10 percent of daily calories and derives 60 to 80 percent of calories from fat, forcing the body into ketosis—a metabolic state where it burns stored fat for fuel. In the short term, people do lose weight and see improvements in blood glucose levels. But the federation's review of the evidence, drawing on a 2021 analysis published in Frontiers in Nutrition, found that keto is no more effective than other diets over the long term. More troubling, the research linked ketogenic eating to increased risk of chronic kidney disease, cardiovascular disease, cancer, diabetes, and Alzheimer's disease—partly because the diet eliminates protective foods like vegetables, fruits, legumes, and whole grains, while emphasizing red meat, processed foods, and saturated fats. LDL cholesterol can rise dramatically in some people. The researchers concluded that for most people, the risks outweigh the benefits.

Detox diets promise to purge the body of toxins through juices or extreme restriction, a particularly seductive pitch after holidays or vacations. Picchio was direct: there is no scientific evidence that detox diets deliver real benefits. The liver and kidneys already handle detoxification. What detox diets do deliver are risks—low blood sugar, muscle loss, and dangerous electrolyte imbalances. Scientific societies do not recommend them.

Traditional ultra-low-calorie diets promise rapid weight loss through severe restriction. The weight does drop quickly, but studies show it bounces back, often accompanied by significant muscle loss. The risks include irregular heartbeat, electrolyte imbalances, dangerously low blood pressure, and eating disorders. These diets belong only in specific medical situations.

So what does work? The federation pointed to three principles any healthy eating pattern must meet: metabolic and cardiovascular safety, sustainability over time, and alignment with each person's individual health situation. By that standard, the Mediterranean diet and the DASH diet stand out. They have decades of research behind them. No trendy diet has yet proven superior to these models in any sustained way. Picchio's final word was not prohibition but precision: trendy diets and intermittent fasting may help certain patients in certain circumstances, but they are not universal solutions and they carry real risks. The answer, always, is education, personalized evaluation, and medical and nutritional guidance—especially for anyone with chronic disease or cardiovascular risk.