Obesity is a worldwide epidemic. Being overweight increases your risk of heart disease, cancer, strokes, and other health issues. Traditional weight loss plans depend on restricting intake at every meal, which some people find unpleasant. Intermittent fasting is a dietary modification that can give you the desired results without dissatisfaction all the time.
Intermittent fasting can be alternate-day fasting, one or two days a week fasting, or eating during a short period each day (time-restricted feeding). These methods reduce your calorie intake, which is vital for any weight-loss effort. It also forces your body to use stored glycogen and fats, generates ketones, and improves your metabolism. Intermittent fasting is associated with lipolysis (fat breakdown), fat oxidation, andbody fat mass reduction.
While eating, we usually consume more energy than is immediately needed. This additional energy is stored first as glycogen (a carbohydrate). When the glycogen stores have reached their limit, additional energy is converted to fat for storage. As long as we eat throughout the day, the stores remain. Fasting forces the body to mobilize the stores of glycogen and fat.
Intermittent Fasting Plans
Various intermittent fasting regimens are named for their eating and fasting periods. Intermittent fasting 20/4, for example, is a plan that allows you to eat during a four-hour period every day. It requires you to eat nothing during the 20-hour fasting period.
Similarly, 18/6 intermittent fasting means your eating window is six hours every day. Obviously, you fast for the other 18 hours. When on a 14/10 fasting plan, you eat for 10 hours and fast for 14.
The most extreme plans are the OMAD (one meal a day) plans, which allow you to eat only once during a 24-hour period. Such plans force your body to use up stored fat for energy during the prolonged fasting period. These plans can be combined with ketogenic diets (called OMAD keto plans).
Intermittent fasting plans place fewer restrictions on what you eat than traditional weight loss plans. You can have water, black coffee, and other beverages that don't provide calories during the fasting period. You can follow your chosen plan (14/10 intermittent fasting, 18/6 fasting, etc.) every day or only one or two days a week.
Intermittent fasting is a useful option for people who don't enjoy restricting their food at every meal. Besides, your body may adapt to low-calorie diets when used for a long time, making this measure less effective for weight loss. Intermittent fasting alternates between low-calorie and normal eating and avoids this problem. Many people find it easier to stick to intermittent fasting plans.
Intermittent Fasting — the Evidence
Intermittent fasting is an effective way to reverse obesity and improve your health by reaching a healthy weight. People adhering to the plan lose 0.8% to 13% of their baseline body weight. There is a reduction in body mass index (BMI) of 4.3%, and waist circumference reduces by 3 to 8 centimeters.
Intermittent fasting can help you lose some weight even without diet control. However, combining time-restricted eating with a diet plan that restricts calories to 30% less than the calculated energy requirements yields greater weight loss.
Apart from weight loss, intermittent fasting also improves health conditions like diabetes, heart disease, cancers, and nervous system disorders. People on intermittent fasting have reduced total cholesterol, triglycerides, and low-density lipoprotein (LDL), which benefit heart health.
It is also believed to increase lifespan, though evidence from human studies is not yet available. These benefits are not all caused by weight loss. During periods of fasting, the body switches from using glucose as the energy source to ketones. These molecules are derived from fats and have potent effects on your body's organ systems.
Intermittent Fasting — the Content
Intermittent fasting plans don't require abstinence from your favorite foods as long as they're not unhealthy choices. However, since you're trying to improve your health, it is best to include nutrient-rich foods from various food groups:
Protein foods such as lean meat, fish, eggs, seeds, and nuts
Whole grains like rice, barley, oats, and wholegrain pasta
Vegetables — leafy greens
Fruits such as pears, apples, bananas, berries, and oranges
Healthy fats like olive oil, coconut oil, and avocado
Dairy — opt for low-fat choices of milk and yogurt
In general, you should plan your meals so that you meet your daily requirements for energy, proteins, and other nutrients. A healthy diet contains about 55% of your daily calories from carbohydrates, 25% from proteins, and 20% from fats. Saturated fats should be less than 10% of your daily calories.
Some foods are simply incompatible with weight loss. Even if you only eat for a short period of the day (for example, the 20/4 intermittent fasting plan), you should avoid sugar, syrups, refined grains, processed foods, fast food, butter, cheese, and others that are calorie-rich and nutrient-poor. Intermittent fasting with compensatory overeating isn't the way to go.
Intermittent Fasting — the Math
Intermittent fasting works, whether you choose 20/4 fasting, 18/6 fasting, 14/10 fasting, or another combination that works with your work and life schedule. However, all diet plans have to meet the mathematical target of calorie deficit. Without it, weight loss is not attainable.
Your body needs a certain amount of energy to carry out the functions of living and doing activities. Even if your work and lifestyle are sedentary, your body needs energy for breathing, digestion, and other essential functions. Your resting energy requirement depends on your gender, weight, height, and age. Depending on your physical activity levels, your daily calorie requirement may be much higher.
A dietitian will calculate your energy requirement using one of several formulae available. They will then plan your daily diet to include enough proteins and other nutrients while limiting your calorie intake. For example, if your daily requirement is 1,900 calories, your dietitian may plan a 1,500-calorie-a-day diet plan for you. This will establish a 21% calorie deficit, leading to a gradual but definite weight loss.
You probably shouldn't agonize over 14/10 vs 16/8 intermittent fasting plans. Calorie restriction is the foundation of any weight loss program, and you must formulate and stick to a diet plan that maintains a negative calorie balance, along with a significant fasting period. As long as you eat fewer calories than you consume and force your body to use up stored energy, you will meet your weight loss goals.
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Is Intermittent Fasting Safe for You?
You should always consult your doctor before beginning any diet and exercise plan for weight loss. They will review your health situation and any medications before advising you. In general, intermittent fasting should be approached with caution if you have any health conditions like kidney disease, diabetes, or heart disease.
Intermittent fasting for women is safe, but you must be sure you're not pregnant. Fasting is also not recommended when breastfeeding. Growing children and adolescents are also not good candidates for fasting programs.
Is Intermittent Fasting Enough?
A calorie-restricted diet is crucial for weight loss when you start your effort to reach a healthy weight. However, relying only on dietary measures is unwise. While a diet plan works for losing weight and reaching a healthy weight, physical activity is essential to keep the pounds from returning.
People who adopt an exercise program along with dietary measures are more likely to maintain the weight loss. Regular physical activity also keeps your heart, muscles, and bones strong as you lose weight. Exercise also improves your mental health and mood and helps you sleep better. For older people, exercise reduces the risks of falls and injuries.
Harvard TH Chan School of Public Health: "Diet Review: Intermittent Fasting for Weight Loss."
National Health Service: "Intermittent fasting."
National Institutes of Health: "Research on intermittent fasting shows health benefits."
National Library of Medicine: "5 questions about intermittent fasting."
National Library of Medicine: "Exercise key to keeping weight off."
National Library of Medicine: "Benefits of Exercise."
Tinsley GM, La Bounty PM. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews 2015; 73: 661-674
Welton S, Minty R, O'Driscoll T, Willms H, Poirier D, Madden S, Kelly L. Intermittent fasting and weight loss: Systematic review. Canadian Family Physician. 2020; 66: 117-125.
About the Author
Amanda Kauffman is a healthcare writer with a passion for providing accurate and useful information to readers. With a background in biology and nutrition, Amanda writes about the human body, diet, and diseases that impact humans.
She is deeply committed to empowering individuals to make informed decisions about their health, as she believes that our choices have a great impact on our health outcomes. This drives her to research and write about a wide range of topics, including preventive measures, treatments, and the latest scientific developments in healthcare.
Amanda is thrilled to be working with Diagnox, a company that shares her vision for improved healthcare delivery for all. Through her writing, she hopes to inspire and educate readers to take control of their health and make informed choices that will lead to a happier and healthier life.
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