Fasting “crash” diets can be dangerous if you’re obese: The quick release of fat gathers around your heart, compromising heart function

Crash diets, also known as meal replacement programs, continuously gain attention because these can help in losing weight, decreasing blood pressure, and reversing diabetes. However, these may have adverse effects on the heart.

A new study presented to the European Society of Cardiology found that crash diets, or those with very-low-calorie content, can increase the fat levels around the heart and cause the heart function to decline. The study was carried out by a team of researchers from the University of Oxford who looked at the effects of a very low-calorie diet on the function of the heart.

In conducting the study, the research team assessed 21 obese participants with an average age of 52 and a body mass index (BMI) of 37 kilograms per square meter (kg/m²). The study participants ate a very low-calorie diet of 600 to 800 kilocalories (kcal) every day within eight weeks. The researchers used magnetic resonance imaging (MRI) to examine the impact of crash diets on the heart function and the distribution of fat in the abdomen, liver, and heart muscle at the beginning of the study and after the first and eighth week.

In the first seven days, the total body fat, visceral fat, and liver fat fell by an average of six percent, 11 percent, and 42 percent, respectively. At the same time, insulin resistance, fasting total cholesterol, triglycerides, glucose, and blood pressure significantly improved. The heart fat content of the participants increased by 44 percent. This was linked to a slump in heart function like the ability of the heart to pump blood.

“The metabolic improvements with a very low-calorie diet, such as a reduction in liver fat and reversal of diabetes, would be expected to improve heart function. Instead, heart function got worse in the first week before starting to improve,” said Jennifer Rayner, lead author of the study.

By the eighth week, the heart fat content and function improved. Likewise, all other measurements, such as body fat and cholesterol, continued to improve.

Rayner explained that the abrupt decline in calories causes fat to be released from various parts of the body into the blood and be absorbed by the heart muscle, which opts to select between fat or sugar as fuel. Moreover, the heart muscle being immersed in fat exacerbates its function.

“After the acute period in which the body is adjusting to dramatic calorie restriction, the fat content and function of the heart improved,” she said.

When adhering to crash diets, healthy people may not feel the difference in heart function in the initial stages. However, those with existing heart disease should be cautious when eating a low-calorie diet as their condition could get worse. Rayner also said that diets with extremely low-calorie content do have benefits, but it must be done with caution and supervision. (Related: Crash diet found to REVERSE Type 2 diabetes in three months.)

Heart-healthy foods

Maintaining a healthy weight does not mean that the health of the heart should be compromised. Listed below are foods that both support heart health and maintain a healthy weight.

1. Fish – Fish rich in omega-3s, such as salmon, tuna, mackerel, herring, and trout, can help reduce the risk of heart disease.
2. Nuts – Healthy nuts, such as almonds and walnuts, will keep you satiated and help the heart function well.
3. Berries – Berries like blueberries, strawberries, cranberries, and raspberries are rich in heart-healthy phytonutrients and soluble fiber.
4. Dark beans – Kidney beans or black beans are packed with fiber, B vitamins, and minerals that keep the heart healthy.
5. Vegetables – Vegetables, particularly the red, yellow, and orange ones, are rich in carotenoids, fiber, and vitamins that support heart health.

If you’d like to read more news stories and studies on different diets, please go to Nutrients.news.

Sources include:

Science.news

ScienceDaily.com

Health.CleavelandClinic.org

Health.Harvard.edu