The Best Way to Do Intermittent Fasting

The best approach to intermittent fasting for patients’ heart health may be a combination strategy, according to Andrew M. Freeman, MD, director of cardiovascular prevention and wellness at National Jewish Health in Denver.

Freeman, who serves as co-chair of the American College of Cardiology’s nutrition and lifestyle workgroup, answered MedPage Today‘s questions about the popular diet. A lightly edited transcript follows.

What should healthcare professionals know about intermittent fasting?

First, I usually tell everybody that there are always going to be fad diets and changes to the status quo that sometimes really are quite beneficial and sometimes not. Fasting has been around for eons. Human beings did not always have food abundance like we have today. And so fasting is probably a natural thing, which is why we store fats.

In short, fasting is a great way to become more mindful about your food choices and when you eat and what you’re eating. When you’re only eating, say, 4 hours out of the day or 6 hours out of the day or even 8 hours out of the day, you really limit yourself. The goal then is to become mindful about what you’re doing and how much you’re doing rather than the so-called mindless eating which we find everywhere.

For doctors and other healthcare providers, you know all it takes is a quick walk to the doctors’ lounge or the nurses’ lounge or any lounge for that matter. It’s loaded with all sorts of bad snacks and fried foods and whatnot. It’s easy to graze throughout the day on really high-calorie unhealthy foods.

What are the cautions when thinking about intermittent fasting?

What I usually tell folks is to be careful which patients they talk to about this, because some people are definitely not the right candidates. If you have a brittle diabetic or somebody who suffers from hypoglycemia or syncope, this may not be the right approach.

The way intermittent fasting works is, for the vast majority of people, they only eat during a set period of time during the day. But I also want to point out that it’s really important that if you gorge yourself on super high-fat pizza and bacon and whatever while you’re eating in that short period of time, it’s going to end up probably doing the opposite and make people gain weight.

Now as for the data, the data that’s out there is overall pointing to that this may be a good way for people to lose weight and maybe improve their health. But it’s important that it be done well. I think the data right now is limited but is suggesting that it may work out. Now this doesn’t negate the fact that the only diet ever proven in all of the medical literature to reverse heart disease is a low-fat, whole-food, plant-based diet.

So what I usually tell people to do is if you’re going to intermittently fast, eat really good quality food when you are eating. Meaning, you want to eat mostly fruits, whole grains, vegetables, and really stay away from a lot of the processed foods and animal products. The goal is not to get 3,000 calories in one meal, but rather during that short period of time that one might be eating to eat a variety of plant-based whole food. I think that together is probably where there’s going be some real synergy.

It does take the body a little getting used to. If you’re used to eating every couple of hours and then all of a sudden you cut down to you know 4 hours a day, the first few days are going to be rough for a lot of folks. Your body has to get used to it, but after that it seems to be quite beneficial and there appear to be some signals out there in the literature that this could affect diabetes in a positive way and help with weight loss and so forth. This is definitely worth a try and may be a lifestyle for the rest of one’s life, but it’s important to eat well when you’re eating if you’re going to intermittently fast.

How does this interact with the data around eating versus skipping breakfast?

It’s a great question. There’ve been a good handful of studies in the last 2 to 3 years that suggest that people who eat breakfast actually do better from a cardiovascular perspective. That stands in contradistinction to intermittent fasting. However, the concept of breakfast — breaking the fast — is not clear. If you have breakfast at 2 p.m., is it still breakfast? The answer to that question, I don’t think we really know yet. If you do best when you eat breakfast, you might want to continue that trend. But if you’re trying to lose weight and have had a lot of trouble doing so, it may be worth a trial. For a lot of folks, the body does a lot to hold on to calories — it does almost anything it can to maintain one’s weight where it is. It kind of becomes a set point. To get that set point to move sometimes requires really intensive effort — a radical shift in the way one functions, and this may be one way to do it.

What is the worst thing you can do for your heart from a diet standpoint?

There are probably lots of worst things you could do. The “Standard American Diet,” with the acronym SAD, is truly sad. In this country, we have a terrible epidemic where you work hard your whole life, you save your money, when you’re ready to retire you suffer heart attacks, strokes, dementia, peripheral arterial disease, and erectile dysfunction if you’re a man. These are all vascular diseases, and most are preventable. It’s the American lifestyle, the Western lifestyle, which is largely sedentary and largely eating highly processed and largely animal based.

What about the keto diet?

I’m not a particularly big fan. It does appear to help some people to lose weight but not everybody and it actually significantly increases cardiovascular risk in terms of cholesterol. I usually tell people to consider avoiding it, unless they have a very strong reason. Now there is some data suggesting that with all that weight loss that occurs that some of those folks do get better in terms of diabetes, but I’m not sure for how long and I’m not sure for how long they can stay cardiovascular disease risk free at the same time. Most of the major nutrition icons out there who are far smarter than I am and have been doing nutrition research will tell you pretty much the same, that it does appear to make people thinner in a lot of cases but it may not improve overall health for the long term.