Can intermittent fasting (IF) reduce the risk of heart attack in the young? Does a low cal diet protect the heart?

Fasting means not eating or drinking for a certain period of time. You could do this by intermittent fasting, which is easier to follow as you can eat within a fixed time window of eight to ten hours, alternate day fasting or calorie-counting, where you cut down calories to below-normal levels. “What happens when we ingest food is that it gets broken down into their simplest forms, like glucose (sugars), amino acids (that make up protein) or fatty acids (that make up fats). The broken-down food is then absorbed into the bloodstream from the small intestine and the nutrients are carried to each cell in the body. What we need to worry about here most is glucose, which is the worst inflammatory agent. This erodes the endothelial or the inner lining of the arteries and veins in the heart. Every time we eat a meal, there is some assault on the endothelium. So a fasting cycle, for example the intermittent fasting cycle of an eight-hour eating window, leaves 16 hours for the body to repair these cellular walls. An injured endothelium causes plaques. Sugar is the worst enemy of the heart chamber and that’s why people living with diabetes have diffuse coronary artery disease, which is characterised by multiple and continuous plaques in the arteries of the heart. Fasting helps reduce oxidants in the body, which cause inflammation and ultimately clogging of blood vessels,” explains Dr Nishith Chandra, Principal Director, Interventional Cardiology, Fortis Escorts Heart Institute, Delhi.

“You can imagine the damaging impact of oxidised low density lipoprotein (LDL), or the bad cholesterol, which narrows arteries easily. Also, fat cannot harm a person whose endothelium is intact,” he adds.

Detailing the potential mechanisms through which intermittent fasting may impact heart health, Dr Chandra lists them as “weight loss, improved insulin sensitivity, reduced inflammation and enhanced autophagy (the body’s natural process of cellular repair). Weight loss, in particular, can have a positive impact on heart health by reducing risk factors such as high blood pressure, high cholesterol levels and diabetes.”

Dr Ranjan Shetty, HOD & Consultant, Interventional Cardiology, Manipal Hospital, Bengaluru, believes the fasting theory can work in the short-term rather than long-term. “There is no doubt that there is a positive relationship between intermittent fasting and heart attacks, strokes, or coronary artery disease. That’s largely because it helps reduce all the triggers that cause heart attacks. This manner of eating has been known to reduce blood pressure, oxidative stress, cholesterol and triglycerides as well as control diabetes and inflammation. However, I think the most immediate effects of fasting are on body weight, which again is critical to reducing cardiovascular risks. So your body weight drops because of the overall reduced caloric load. Also, the reduced glucose intake means the body draws energy from fat reserves and burns them. But the changes in body weight are discernible in the short-term after which the body readjusts itself to the new food regime and the weight loss tends to plateau out. So I would say fasting formats are good for losing 10 per cent of your body weight initially and then beat the plateau with moderate intensity exercises, which should never be ignored for long-term gains. That the fasting cycle works for cardiovascular health and diabetes management is probably evidenced by the fact that our older generation, who fasted frequently, lives long and relatively disease-free,” says he.

WHAT DOES EXISTING RESEARCH SAY AND WHY IS THERE NEED FOR MORE EVIDENCE?

Both cardiologists point out that research in this area is still evolving, and more studies are needed to establish definitive conclusions. “Larger and more rigorous studies are needed to validate these initial findings. It’s worth noting that individual responses to intermittent fasting can vary, and it may not be suitable for everyone. If you have pre-existing heart conditions or any concerns regarding your heart health, it is recommended to consult with a healthcare professional before starting any new dietary pattern,” advises Dr Chandra.

Dr Shetty feels that any fasting discipline may cause older adults to lose more weight. And some exercisers might overdo their routines in the 16-hour fasting period for faster fat burns. “This could wear your body out and slow down metabolism, which might again cause imbalances. Also, discuss any fasting regime with your doctor first. Fasting may not be a wise option for those with diabetes or those who take multiple medications for blood pressure and pre-existing heart disease. The latter could be more prone to imbalances of sodium, potassium and other minerals during longer-than-normal periods of fasting.”

A 2020 study published in the journal Cell Metabolism found intermittent fasting helped women with metabolic syndrome. As they reduced their eating window to 10 hours, they had lower blood pressure, better cholesterol and fewer blood sugar spikes.

Intermittent fasting could increase a key protein that controls inflammation and protects the heart. “A 2021 study in the European Heart Journal Open showed fasting didn’t reduce LDL but improved insulin resistance, which can increase blood sugar and lead to Type 2 diabetes, and metabolic syndrome, a cluster of conditions that can increase a person’s risk for heart attack and stroke,” says Dr Shetty.

The study’s lead researcher, Dr Benjamin Horne, hypothesised the mechanism might be similar to the way a class of drugs called sodium-glucose co-transporter 2 (SGLT-2) inhibitors work to lower Type 2 diabetes and heart failure risk. The drugs also raise levels of a protein called galectin-3, which controls inflammation. Dr Horne and his colleagues, for example, found that intermittent fasting was associated with a longer lifespan and a lower risk of developing heart failure.

The promising results only emphasise the need for further research to establish a definitive relationship between fasting and heart health. “As always, maintaining a healthy overall lifestyle — including a balanced diet, regular physical activity, and appropriate medical care — is crucial for promoting heart health and reducing the risk of heart attacks,” adds Dr Chandra.