New study examines health benefits of fasting for the heart

Camille Bienvenu
Mon, 11 Dec 2017
New study examines health benefits of fasting for the heart
A new study has reviewed recent evidence about the beneficial effects of intermittent fasting (IF) for the heart.

There is a lot of research on the effects of meal timing and frequency on metabolic health, prediabetes development and the incidence of type 2 diabetes. But far less is known about fasting for heart disease prevention.

Previous research suggests that time-restricted feeding lowers body weight and improves a cluster of metabolic conditions that can lead to heart disease, such as elevated cholesterol, insulin resistance and high blood pressure.

The new study review discusses findings from a recent American Heart Association's (AHA) statement on the subject of fasting and heart health, as well as human studies looking specifically at alternate-day fasting (ADF) and fasting-mimicking diets.

ADF is when one alternates between a day of reduced calorie intake and a free-feeding day. The fasting-mimicking diet (FMD) achieves changes similar to those caused by fasting through lowering calories by half and slashing sugar and protein.

According to Texas Tech University researchers who reviewed the AHA statement, which includes data from ten studies, ADF can lead to an average weekly weight loss of 0.75 kg in some people.

ADF or periodic fasting regimens ranging from six to 24 weeks in length were shown to reduce total cholesterol by six to 21 per cent, LDL cholesterol by seven to 32 per cent and triglycerides by 16 to 42 per cent.

In such a short time, ADF also reduced systolic blood pressure by three to eight per cent, and diastolic blood pressure by six to ten per cent. The greatest improvements were seen in participants who lost six per cent or more of their body weight.

A year-long study comparing ADF to traditional daily calorie restriction in obese people did however find that ADF increased LDL, but this was initially accompanied by higher HDL cholesterol.

In shorter trials of ADF, lasting from two days to 12 weeks in duration, fasting led to improvements in body weight, fat mass, triglycerides, LDL particle size and C-reactive protein, a marker of inflammation and sign of impending heart trouble.

One study showed that a five-day monthly cycle of FMD (made up of about 10% proteins, 30% carbs and 60% fat) for three months reduced waist circumference by 4 cms and lowered fasting glucose by 11 per cent in those with elevated blood sugars.

Although the FMD didn't affect cholesterol levels differently than the control diet, it achieved a 13 to 15 per cent reduction in Insulin-like Growth Factor 1 (IGF-1). High IGF-1 levels tend to be associated with an increased risk for heart failure.

Researchers are still trying to determine whether the benefits of the FMD are attributable to calorie restriction, unique metabolic effects of fasting, or some combination of both.

Further research is needed comparing IF to calorie restriction and investigating long-term improvements in heart disease risk factors with different fasting protocols.

The findings were published in the journal Future Cardiology.
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