Two of the more popular dietary approaches for losing weight these days are intermittent fasting and keto dieting. People claim to have had success with both approaches, but does one offer an advantage over the other for weight loss and overall health? First, let’s look at what each approach entails.
Intermittent fasting is not eating at certain times of the day. Intermittent fasting is not a new trend. It’s an age-old practice used for decades by people around the world. In contrast, the keto diet is a relative newcomer to the scene. You can structure intermittent fasting in several ways:
8:16 Intermittent Fasting
With this fasting schedule, you eat during an 8-hour window period and fast the other 16 hours of the day.
5:2 Intermittent Fasting
With this approach, you eat normally 5 days of the week and reduce your calorie consumption by 75% on the other 2 days.
Alternate Day Fasting
With this approach, you fast one day and eat the next. This fasting is a bit more challenging and not a good one to start with.
Intermittent fasting doesn’t dictate what you can and can’t eat, only that you eat during certain times and fast during others, according to your chosen schedule.
Now, let’s look at the keto diet.
The Keto Diet
With a keto diet, there is no restriction on when you eat, but the composition of your diet changes dramatically. The keto diet is a very low carbohydrate, high fat, moderate protein diet designed to shift your body away from burning sugar to using fat as an energy source. The typical composition of a keto diet is 70-80% fat, 5-10% carbohydrates, and 10-20% protein. When you restrict carbohydrates dramatically, your liver makes ketone bodies from fat, and this becomes your body’s main energy source.
Proponents of the keto diet say following the keto approach can lead to health benefits – weight loss, decreased hunger, and more. After a few weeks, you become what’s called “fat adapted” or “keto adapted,” which means your body switches to burning fat for most of its energy needs. When this happens, you can go longer without eating, and drop weight easier, since your body will be using stored body fat for energy.
Which is a Better Choice for Weight Loss?
Studies show you can lose weight using either approach. Intermittent fasting reduces your overall calorie consumption and creates a calorie deficit that can lead to weight loss. The keto diet shifts your metabolism toward using fat as its primary fuel, making it easier to lose weight and body fat.
The best choice would depend on your health and which you would have an easier time sticking with. Get a physical exam before starting either diet, since neither may be appropriate if you have certain medical conditions, like type 1 diabetes.
Benefits of the Keto Diet
A benefit of the keto diet is it doesn’t restrict calories. You can eat until you’re full, as long as you keep your carbohydrate intake low. To get keto-adapted, you would consume only 20 grams of carbohydrates during the first few weeks and increase the amount to 50 grams of carbohydrates daily. But that’s still not a lot of carbs. Some people have problems sticking to such a low carbohydrate diet. Plus, you’ll need to eat a lot of fat and moderate quantities of protein to make up for the drop in carbohydrates.
The keto diet also has a period of adaptation, around 2 weeks, where your body switches to burning fat over carbs. During this period, you might feel sluggish or even flu-like as your body makes the transition. Some people get discouraged during this phase and want to quit, but it eventually passes. You might discover that once your body shifts to fat-burning mode, you feel more energetic and have more mental clarity.
Another advantage of the keto diet is it curbs hunger and helps keep sugar cravings out of the picture. Once your body becomes a fat burner, you won’t experience the desire to eat junk food or sugar, and you’re unlikely to feel hungry.
In support of the keto diet for fat loss, small studies show that people can lose weight more quickly on a keto diet relative to a low-calorie diet, although some weight loss early on is water weight. One advantage the keto diet has over a low-fat or calorie-restricted diet is that most people don’t feel hungry on a keto diet. A ketogenic diet also lowers insulin and may help with blood sugar control. It also appears to be “protein sparing,” in that you don’t lose significant muscle mass on a ketogenic diet.
A disadvantage of the keto diet is it’s not clear what the long-term effects of being on one are. It’s also hard for some people to stick to a diet that consists of 60% or more fat. It might seem easy at first, but as time goes on, the dropout rate rises.
Benefits of Intermittent Fasting
If you don’t want to change the composition of your diet, and you can’t envision yourself eating so much fat and so few carbohydrates, intermittent fasting might be a better choice. If you choose a plan like the 16:8 or 5:2 plan, it can be relatively painless to follow. With 5:2, you’re only cutting your calories two days per week, and with 16:8, you can eat an early dinner and have a late breakfast the next day. Most people don’t feel deprived on such a plan.
Plus, research shows intermittent fasting may have other benefits, including lowering blood pressure, blood glucose, and inflammation, all risk factors for cardiovascular disease. It’s still important to make healthy food choices on an intermittent fasting diet to maximize the cardiovascular benefits. However, you can avoid the problem of having to consume so few carbohydrates and so much fat. After you get into the swing of things, an intermittent fasting plan, like 16:8, can be relatively easy to maintain.
The Bottom Line
The best diet for weight loss of the two is the one that fits into your lifestyle the best. There’s evidence to support the weight loss benefits of both diets.