Posted on Sep 07, 2020, 4 p.m.
Researchers from National Jewish Health concluded after reviewing existing scientific studies on the trends of intermittent fasting and ketogenic studies that the diets seem to help with short term weight loss and have modest evidence to suggest some cardiovascular benefit, but these diets allow for the consumption of foods known to increase cardiovascular risk and are unlikely to be effective at preventing heart disease as the currently recommended well established nutritional guidelines.
"With diets like keto and intermittent fasting, social and popular media has been flooded with claims, promises and warnings that are at best unverified and at worst harmful to your health," said Andrew Freeman, MD, director of cardiovascular prevention and wellness at National Jewish Health and co-author of the study. "Diets recommended by health experts, such as plant-based and Mediterranean diets, have been extensively studied for safety and efficacy, and demonstrated conclusively to improve cardiovascular health."
The keto diet has become very trendy, this is a very low carbohydrate dietary approach that aims to send the body into a state of ketosis. In this metabolic state, the body has reduced access to glucose and is fueled by mostly fat. Limited study on this diet shows it helps to initially lose weight, but it tends to be unsustainable according to 12-month data, it is also unclear whether the weight loss is caused by ketosis or simply by the calorie reduction.
Experts have expressed concerns about the type and amount of fat that is consumed while on this diet. Existing studies strictly controlled the type of fat and foods that were consumed, but in the real world, people following keto may consume high amounts of unhealthy saturated fats which are associated with the increased risk of high blood lipid levels and heart disease. Additionally, there is evidence that maintaining a keto diet for an extended period of time may lead to stiffening of the arteries, and a greater risk of death.
On the plus side, when monitored and controlled a keto diet does show promise as a potential treatment for diabetes, with some studies showing improved glucose levels, lower fasting glucose and improved insulin levels in mice that were fed a keto diet. But it was noted this was in animals, and further research is needed to confirm these benefits and to assess risks to humans before a keto diet can be clinically recommended.
Experts are optimistic regarding the potential benefits of intermittent fasting which has also become popular. In this dietary plan, there are a wide range of approaches, some go for 8 hours without eating, some 10 or 16, and others restrict meals to certain hours of the day. Studies are showing this approach to be beneficial, but it is not without pitfalls, such as hunger induced by fasting causing people to overeat when it is time for meals, or making unhealthy choices at mealtimes which could potentially have adverse effects on cardiovascular health.
One of the benefits of intermittent fasting is that it can include time while sleeping, and one can start with a lower amount of time and gradually build up. Available data comes from animal and human studies which have shown increased weight loss, decreased blood pressure, improved glucose tolerance, controlled lipid levels, and increased longevity.
"The potential risks of intermittent fasting that require further study include effects of starvation and how it may impact organ function," Dr. Freeman said. "It is particularly important for diabetics to speak with their doctor before trying intermittent fasting to discuss how to control their disease and the risk of hypoglycemia that may come with skipping regular meals."
Many studies show that intermittent fasting can have potent effects on both the mind and body, and it may even help you to live longer. This eating plan cycles between periods of eating and fasting, and it does not specify what to eat rather when you should eat, such as a 12 hour fasting period twice a week, or restricting the daily eating period to be within an 8-hour window and fasting for 16 hours in between only drinking fluids. Fasting is not new, our ancient relatives fasted regularly until food could be found, as such humans evolved to be able to function without food for extended periods of time.
Those using this dietary plan often experience weight loss, this is by both calorie restriction and fasting changing hormone levels to promote weight loss. Studies show intermittent fasting to lower insulin and increase growth hormone levels to release fat-burning hormones which may increase your metabolic rate. One of the downsides of this is the possibility of binge eating, which is why it is recommended to start with a short period of fasting and gradually build up.
The main health benefits of intermittent fasting include weight loss, reduced insulin resistance, reductions in the markers of inflammation, lowered blood sugar levels, reduced LDL cholesterol, lower blood triglycerides, increased BDNF brain hormones, helping to prevent some cancers, and extended lifespan.
However, intermittent fasting is not for everyone such as those with eating disorders, those taking certain medications, those who are underweight, those with blood sugar regulation issues, those with low blood pressure, and women trying to conceive or are pregnant/breastfeeding or with a history of amenorrhea. Intermittent fasting has an outstanding safety profile, and there is nothing dangerous about it for most healthy people. That being said, it is recommended to consult with your doctor or a certified medical professional before beginning any diet.
According to the researchers, while there is modest evidence of favourable effects on the fad keto diet and even more for intermittent fasting, neither dietary approach is recommended for the treatment or prevention of any condition until large long term studies can more definitively examine their impact. Rather than these 2 approaches, the researchers recommend diets that have been extensively studied and scientifically proven to prevent and in some cases even reverse cardiovascular issues. They, along with most experts, recommend a Mediterranean diet, a whole food plant-based diet, and the DASH diet, which all share a common foundation that includes consuming more fruits, vegetables, legumes, nuts and whole grains while avoiding highly processed foods and added sugars.
Materials provided by:
Content may be edited for style and length.
This article is not intended to provide medical diagnosis, advice, treatment, or endorsement.