Intermittent Fasting v Time-restricted Eating v Circadian Eating, what's the difference?

Updated: Apr 14, 2024Veronika Larisova

Intermittent fasting, time-restricted eating, circadian eating…are you confused? Are they all the same or different? Should you fast? Which one to choose? What’s the science behind fasting?

Intermittent fasting

Intermittent fasting is a dietary practice involving alternating fasting periods with periods of normal eating. It has recently gained popularity as a way to lose weight, improve metabolic, gut, and brain health, potentially reduce the risk of chronic diseases such as diabetes and heart disease, and increase lifespan. There’s lots of research backing such claims. We included a few good reviews in our references, but you can find hundreds of recent studies by doing your own PubMed research.

There are several different approaches to intermittent fasting. Still, the most common involve limiting food intake to a specific time window each day (such as an 8-hour "eating window" followed by a 16-hour fast) or fasting for a total of 24 hours or two non-consecutive days per week.

One of the key benefits of intermittent fasting is that it can help reduce overall calorie intake without requiring people to count calories or restrict certain foods. Calorie restriction, the reduction of energy intake without malnutrition, is a dietary manipulation that can improve health and increase lifespan.

A review from 2022 summarised the science-proved benefits:

Positive effects on weight loss even without caloric restriction
Reduced insulin resistance
Favourable shifts in the levels of leptin and adiponectin
Wide range of benefits for many diseases, including obesity, Type 2 Diabetes, and hypertension, and improved cardiovascular risk factors.

A science review from 2021 on the effects of intermittent fasting on brain and cognitive function concluded that intermittent fasting might be protective against developing neurological disorders.

However, it's important to note that intermittent fasting is not suitable for everyone. People with certain medical conditions, pregnant women, or breastfeeding should avoid fasting. Additionally, those who try intermittent fasting should consult a healthcare provider to ensure they do so safely and effectively.

Time-restricted eating

Intermittent fasting and time-restricted eating are similar in that they both restrict the time window during which one consumes food. Essentially, time-restricted eating is a type of intermittent fasting.

Time-restricted eating involves limiting the time during which one eats to a specific window each day, usually between 6 to 12 hours. This approach does not typically involve full day fasts but instead limits the period during which one consumes food daily. Time-restricted eating has been shown to improve metabolic health, and some studies suggest that it may also aid in weight loss.

In summary, intermittent fasting involves more prolonged periods of fasting followed by periods of eating, while time-restricted eating involves limiting the time window during which one eats each day. Both approaches can be practical for weight loss and improving gut, metabolic and brain health, and the choice between the two may depend on personal preference and lifestyle factors.

Circadian eating

Circadian eating refers to the practice of aligning one's eating patterns with their circadian rhythm, which is the natural 24-hour cycle that regulates many physiological processes in the body, including metabolism, hormone production, and sleep-wake cycles. The idea behind circadian eating is that by eating at specific times of day, one can better support these natural biological rhythms and promote optimal health and well-being. Essentially, circadian eating is an early time-restricted eating.

Research suggests that eating in sync with the circadian rhythm can help regulate appetite and metabolism, improve sleep quality, and reduce the risk of chronic diseases such as obesity, diabetes, and cardiovascular disease. Specifically, circadian eating involves eating larger meals earlier in the day and smaller meals later in the day, with the largest meal consumed at breakfast or lunch.

One way to practice circadian eating is to follow a time-restricted feeding pattern, such as an 8-hour eating window, during which all meals are consumed. Another approach is to aim for consistency in meal timing each day, with meals spaced out evenly throughout the day. Shifting your eating window by just a couple of hoyrs can give you jetlag symptoms.

Our recommended fasting protocol

At Chief, we like to be in tune with nature, so we love the circadian eating protocol with 8-10 hours eating window. This is how we do it:

BREAKFAST

Break the fast at 8-11 am (depending on how long you fast on the day. We do a longer fast on lighter days and days off training and a shorter fast on heavy training days). We usually train in the morning and start work around 9 am, so we break the fast with a coffee and Chief bar to cover our protein intake required post-training.

LUNCH

We have lunch whenever we get hungry during the day, and it’s our largest meal for the day. Our lunches are homemade and consist of:

A huge veggie bowl with olive oil and fresh herbs for polyphenols and delicious natural flavours
Avocado or nuts for good fats
Meat, fish, chicken, or eggs for protein. Often, we throw a bag of biltong or chopped-up beef bar into the veggie bowl.
A small serving of carbohydrates on heavy training days, such as ½ cup sweet potato or legumes or ¼ cup cooked quinoa

DINNER

Dinner no later than 5-6 pm for optimal gut health, sleep, recovery, and anti-aging.

Dinners usually consist of non-starchy vegetables of any style (veggies bowls, salads, stews, curries, stir-fries) and protein (meat, chicken, fish) or broth-based soups if we aren’t too hungry, which often happens if we snack during the day.