This question is a classic case of conflicting advice, isn’t it?
For years we were told that skipping meals would slow our metabolism and make us fat, then along came the 5:2 diet and we were told intermittent fasting was the secret to good health. Everyone has a friend who lost weight once they started eating breakfast, and another who lost weight by skipping the same meal. Which is right?
Firstly, it depends what you mean by “healthy”. If you’re eating too much and need to lose weight for your health, then some form of calorie restriction will often help.
Secondly, it depends on how you skip meals. If you’re intentionally following an “intermittent fasting” diet (see box), research results are more positive. If you find yourself skipping meals, but then making up for it by eating extra later in the day, this can be less than ideal.
So let’s get the big one out of the way first: weight loss.
Does skipping meals help you lose weight?
Most studies indicate that purposely fasting either a few times a week, or say 16 hours a day, can promote fat loss. A study of people who fasted every second day found weight loss of 3–8% over the course of 3–24 weeks. What’s more, much of the weight loss was belly fat. Other studies indicate this weight loss is less clear-cut for women. Women’s bodies often respond differently to intermittent fasting, and it can cause hormonal imbalance and lower women’s glucose tolerance levels – which can cause weight gain later. It also depends on your emotional and physiological reaction to hunger. Some people can skip meals, and then eat normally after. Other people can be triggered by the all-or-nothing approach and find that skipping meals causes them to overeat or even binge.
Let’s look at some other health indicators:
Immunity: A study of mice who fasted for two days found the mice had an increase in new white blood cells, which is good for immunity. However, another study by the University of Bath (using humans this time) found that fasting could increase susceptibility to infection in the long term.
Insulin resistance and type 2 diabetes: Studies show intermittent fasting can reduce blood sugar levels and fasting insulin.
Heart disease: A study in Cell Metabolism found that periodic fasting was linked to lower risks of heart disease, diabetes, cancer, and aging.
What if you accidentally skip a meal?
All these studies assume you are purposely skipping meals in a structured way. If your lifestyle is chaotic right now, and you accidentally skip lunch, or even dinner, it’s OK. Chances are your metabolism will not grind to a halt. Although you might find yourself getting a little irritable, and you need to make sure you’re getting enough nutrients the rest of the time.
In summary: skipping meals or intermittent fasting can help some people manage their weight, but it doesn’t work for everyone. If you’re planning a significant change in your eating patterns, consult your doctor first.
What is intermittent fasting (IF)?
Intermittent fasting refers to going for longish periods of time without eating, and then eating normally the rest of the time.
The most popular way to do this is the 5:2 diet created by Dr Michael Mosley. The 5:2 refers to fasting for two days and eating normally for five. On the two days, you restrict your intake to 500 calories for women and 600 for men. You can use these calories over the whole day, or eat them all at once, it doesn’t matter. On the five days, you eat whatever you want. Other forms of IF including fasting every second day, or fasting for a certain number of hours a day.
Remember, we all fast: when we sleep. If getting through a whole day on just 500 calories makes you twitchy, you might find benefit in fasting 12 or 16 hours a day instead. Give yourself a window in which you can eat (eg 8am to 8pm, or 10am to 6pm), and then stay away from food for the rest of the time.