How To Start Intermittent Fasting For Weight Loss

Weight loss can be incredibly challenging. People typically try several diets before finding one that helps them sustainably lose weight and improve their health.

A popular diet is intermittent fasting (IF), known for its accessibility and easy-to-follow process.

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What is intermittent fasting (IF)?

Unlike many diets that focus on the specific foods you can't eat, IF is all about when you can eat. On the IF diet, you can only eat during a set window of time, and you'll be fasting for a certain amount of hours each day. This process can help your body burn fat, optimize digestion, and produce various health benefits.

Researchers and avid followers of IF say our bodies naturally evolved to go without eating for hours, or even a day or two. In prehistoric times before the rise of modern agriculture, we were hunters and gatherers, and this lifestyle allowed early humans to survive and thrive for extended periods without eating. Hunting for meat and gathering nuts and berries required a lot of time and energy.

However, with the rise of technology, food establishments, and supermarkets open 24/7, we're sitting and snacking all day. This snacking can mean a net increase in calorie consumption, resulting in a higher risk of obesity, heart disease, and a constant high insulin level throughout the day.

Periods of lowered insulin levels are important as they allow for fat burning. These decreased levels also improve your body’s sensitivity to insulin, reducing the risk of developing type 2 diabetes.

The health claims

Research claims that IF provides many benefits due to several factors, including activating hormonal changes, encouraging mindful eating, and triggering a "metabolic switch," which burns more fat¹.

A recent 2020 review looked at various studies investigating the effects of IF on heart health. Researchers found the body switches from using glucose as energy to ketones and fatty acids, known as intermittent metabolic switching. IF is positively associated with preventing and improving multiple cardiovascular risk factors such as diabetes, hypertension, and obesity. IF is also linked with improved outcomes after a cardiac event².

Intermittent fasting has increased in popularity due to its weight-loss benefits, with its effects being comparable to a continuous calorie deficit in overweight and obese adults³.

Studies show that the benefits achieved from IF come from the metabolic shift, which improves insulin sensitivity, cardiac function, and blood pressure⁴. A 2020 review looked at IF for treating obesity. All the trials included in the study found weight loss ranging from 0.8-13% with no adverse side effects, with comparable results to a traditional calorie-restrictive diet⁵.

Ways to do intermittent fasting

You can do intermittent fasting in several ways. They are all based on choosing regular fasting and eating periods that suit your lifestyle and preferences.

You can try only eating during an 8-10 hour period each day and fast for the rest of the 24 hours. Alternatively, fasting every other day may be more sustainable for you, so you can choose to eat only one meal a day several times a week.

Generally, there are three broad types of intermittent fasting:

  • Alternate day fasting: Alternate between fasting and feasting days: You fast one day and eat the next. 

  • On the days that you are fasting: You try to consume only 25% of your normal daily calories

  • On your non-fasting days: You can eat your normal daily calories in the normal meal pattern that you usually follow. 

  • A 5:2 diet: Like the alternate day fasting, except you eat normally for five days a week and fast for two. 

  • Time-restricted eating: You shorten your eating period to 4-10 hours a day. 

  • While there's no calorie restriction, you fast outside of that eating window. 

  • Most people like 16:8 fasting, where you eat within an eight-hour window and fast for the other 16 hours.

Despite not having calorie restrictions in the non-fasting periods, it is important to use common sense in what you consume. If you always eat calorie-dense foods high in fat and sugar, you will be countering the health benefits achieved by the fasting period. The calories will eventually pile up, making it difficult to lose weight despite fasting.

It's important to note that fasting for extended periods like 24, 48, or 72 hours may be dangerous, and it’s not necessarily better for your weight loss goals. In fact, not eating for too long may encourage your body to go into "starvation mode" and store more fat⁶.

It can also take several weeks before the body gets used to fasting. According to a 2021 study, the limited caloric allowance on fasting days caused too much discomfort and hunger for many participants, so they stopped the diet⁷. It's normal to feel hungry for a little while adjusting to IF; however, talk to your doctor if you have any concerns.

Tips to help you with intermittent fasting

1. Start slow and ease into your new fasting plan

While it’s tempting and incredibly exciting to jump right into your new eating and fasting routine, this can be difficult and leave you hungry. Give your body some time to adjust to this new eating style and gradually increase your fasting hours over a few weeks.

2. Listen to your hunger signals

Are you hungry, or are you just bored and looking for something to snack on? Perhaps you've been trying IF for a while and feel extreme hunger, dizziness, or weakness during fasting periods.

Try adding more nutrient- or calorie-dense foods like nuts, healthy fats, and protein during your eight-hour period. Make sure to also stay hydrated throughout the fasting and non-fasting period.

You could also consider using vitamin supplements during the fasting period as they are virtually calorie-free and could give you an energy boost while fasting.

3. Try different fasting periods

While a popular fasting period to start with is 16:8, you can play around with what suits you based on your lifestyle. For example, if you know you'll be going out to eat out with friends on the weekends, you can try the 5:2 weekly diet and reduce calorie intake on the weekdays.

A great part of intermittent fasting is how flexible and adaptable it is to your schedule.

4. Change your workout regime and schedule

If you're pairing intermittent fasting with exercise to boost weight loss, you might want to plan certain types of exercise. If you’re exercising in a fasted state, exercise first thing in the morning when you have the most energy. Likewise, if you want to do more HIIT-style or strength-building exercises, save those exercises until after you've eaten.

Restricting calories and fasting can lead you to lose muscle and fat, so exercise can play an important role in maintaining muscle mass⁸.

5. Focus on protein

Protein is one of the three macronutrients (carbohydrates, fat, protein), and it requires more energy to digest, so it burns more calories. Protein also keeps you feeling fuller for longer, which is exactly what you need when you’re fasting for long periods. To avoid sharp insulin spikes, break your fast with protein.

Ensure you eat enough protein during non-fasting periods to counteract any muscle loss. Protein will help you build/maintain muscles during exercise and rest.

The lowdown

Intermittent fasting (IF) is a flexible way to reach and maintain a healthy weight. By incorporating a fasting period within your eating schedule, you'll be able to achieve numerous health benefits, including weight loss.

Before starting intermittent fasting, it’s best to check with your doctor to ensure it's the right plan for your health goals and history.

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