What's the best time of day to eat?

How can the time I eat affect my weight?

According to recent research, eating the majority of our daily calories earlier in the day is better for us – preventing weight gain, stabilising blood sugar and reducing the time that blood sugar is above normal levels. Why should this be the case? Well, studies suggest that calories consumed at different points in the day may have different effects on our energy use and our circadian rhythm.

One of the reasons is that, as the day draws to a close, the body begins to release the sleep hormone, melatonin, which results in less insulin and affects our ability to digest sugars, like glucose.

Insulin has a circadian rhythm – levels are naturally higher in the morning and afternoon. This means that, for the majority of us, our bodies are better equipped to manage the glucose from digestion earlier in the day. What’s more, eating a large meal too close to when your body is shutting down to rest, may be a risk factor for chronic disease, including diabetes.

Consequently, skipping breakfast and eating a greater proportion of your calories later in the day is likely to encourage the body to store more fat, while snacking after dinner, has been seen to result in fat gain.

To put this to the test, researchers put 10 people with prediabetes and obesity into two groups, one restricting their calories to the first eight hours of the day, creating a fasting window out of the remaining 16 hours; the other eating 50 per cent of their daily calories after 4pm for seven days. They concluded that eating earlier has a range of benefits, including improving metabolic health and potentially preventing diabetes.

Consequently, consuming the majority of your calories at breakfast and lunch may make it easier to control your weight, avoid fat gain and lower your risk of diabetes, especially at mid-life. So, if you follow a fasting routine, how can you apply this knowledge?

What is fasting?

When we refer to ‘fasting’ we’re talking about the abstinence from all or some food and drink for a given period of time.

You may also see it referred to as ‘intermittent fasting’ or ‘time restricted eating’; both these terms suggest eating patterns that expand the amount of time your body is in a fasted state.

This state is achieved by reducing your ‘eating window,’ or the time during which you eat.

What are the health benefits of fasting?

Fasting appears to have several benefits including helping your body use stored body fat more easily; increasing the diversity and number of beneficial bacteria in the gut; and reducing some of the risk factors for heart disease such as high blood pressure and cholesterol.

Animal studies have shown that fasting may delay ageing and promote levels of human growth hormone, which plays an important role in the body’s repair mechanisms; and improve brain function, particularly in people with Parkinson’s and Alzheimer’s.

Learn the top 10 health benefits of fasting

Listen to the BBC Good Food podcast, fasting for weight loss; read more on healthy ways to lose belly fat and the dangers of abdominal fat

Is fasting safe for everyone?

Fasting should be avoided if you’re underweight, if you have or are recovering from an eating disorder, are pregnant or breastfeeding.

Before starting a new diet, speak to your GP, particularly if you’re under 18, elderly, have a pre-existing medical condition (including diabetes, high blood pressure, kidney stones, acid reflux) or are on medication.

For women of reproductive age, the timing of a fast may be best performed during the follicular (early) stage of the menstrual cycle.

Fasting diets compared

There are different ways to incorporate fasting into your daily or weekly plan.

The 5:2 diet

The 5:2 diet was created by the late doctor Michael Mosley in 2013.

The rules are simple: dieters eat ‘normally’ for most of the week but on two non-consecutive days they eat just 25 per cent of their usual calorie intake (500 calories for women and 600 for men). Women are expected to lose about 1lb a week, although men may lose more.

On ‘fasting’ days, people are advised to choose nutrient-dense foods such as lean protein including poultry and vegetables rather than calorie-counted ready meals, which aren’t as satisfying.

Some people report feeling tired, experiencing poor concentration, headaches and dizziness on fasting days so staying hydrated with water and herbal tea is important.

Learn about how to go on an anti-inflammatory diet

The 16:8 diet

Similar to the pattern of eating analysed by the researchers from NYU’s medical school in its study (see above), this is where the day’s eating is concentrated into an eight-hour window.

The Fast 800 diet

Another diet, originally created by Dr Michael Mosley, this regime is aimed at rapid weight loss and is not recommended for people who are underweight or have an eating disorder, are type 1 diabetics, have had a heart condition or are recovering from surgery or doing any endurance exercise.

In stage one, lasting between two and 12 weeks, participants eat 800 calories a day of lean protein and vegetables to prompt the body into ketosis, which burns fat.

In stage two, participants eat 800 calories for two days a week, following a low-carb Mediterranean diet for the remaining five days.

Stage three is the maintenance phase when participants continue with a low-sugar, Mediterranean-style of eating.

Side effects may include hunger pains, headaches and constipation and up to three litres of water is recommended a day to overcome tiredness.

Read more about what you can eat on the 800 fast diet.

So, when is the healthiest time to eat?

Starting your day by eating breakfast within two hours of waking and setting a curfew for nighttime meals and snacks may reduce hunger and help control your overall calorie intake. If you’re not hungry at breakfast, it may be that eating late in the evening is affecting your appetite – making changes may improve appetite first thing and bring numerous other health benefits, too.

What’s the best time of day to eat?

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