How is a Fad Diet Different Than a Low Calorie Diet?

A fad diet is a diet that is often advertised as the newest way to lose weight fast or improve your health.

By: Michael Pollan, Published on: 2023-10-30, Last Updated: 03-07-24

Reviewed by: Huria Saleem

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Every day, we hear about new diets that promise to help us lose weight, feel better, or reach some other health goal. With so many options, it can be hard to know which diets are actually good for us and which ones are just passing fads. Two terms we often hear when talking about weight loss and health are "fad diets" and "low-calorie diets." But what are they? And how are they different? In this guide, we'll look at what each type of diet is, its pros and cons, and some examples.

What is a Fad Diet?

A fad diet is a diet that becomes popular quickly and is often advertised as the newest way to lose weight fast or improve your health. These diets are usually based on attention-grabbing ideas and promises, but they might not always have strong scientific evidence to support them. Fad diets often have strict rules about what you can and cannot eat, and while they might help you lose weight in the short term, it's often hard for many people to follow them for a long time.

What is a Low-Calorie Diet?

A low-calorie diet is a diet where you consume fewer calories than your body needs to maintain its current weight. This creates a calorie deficit, which leads to weight loss. Low-calorie diets are not about the specific type of food you eat, but rather the quantity. They are often recommended by healthcare professionals and are based on proven principles of weight management.

To lose weight using a low-calorie diet, you need to track the number of calories you consume each day and make sure you are in a calorie deficit. You can use a TDEE Weight Loss Calculator to estimate your daily calorie needs, and then track your calorie intake using a food journal or calorie tracking app.

Key Differences Between Fad Diets and Low-Calorie Diets

1. Sustainability

Fad diets: These diets often involve eliminating certain food groups or consuming specific foods in large quantities, making them difficult to sustain over the long term. After a while, many people find it challenging to stick to such restrictive patterns and return to their previous eating habits.

Low-calorie diets: A low-calorie diet is more about reducing the overall amount of food you eat rather than cutting out specific items. Because of this, it can be easier to maintain for extended periods as it allows for a broader range of food choices.

2. Effectiveness

Fad diets: While some people might see immediate weight loss results, the effects are often temporary. Once they stop the diet, the weight often returns, sometimes even more than before. This phenomenon is commonly referred to as the "yo-yo effect."

Low-calorie diets: When followed consistently and combined with regular exercise, low-calorie diets can lead to steady and lasting weight loss. The key is consistency and ensuring you're getting a balanced intake of nutrients.

3. Safety

Fad diets: Because fad diets can be restrictive and sometimes eliminate essential food groups, they can sometimes be unsafe. They might lead to nutrient deficiencies or other health issues if followed for too long.

Low-calorie diets: These diets are generally safe, especially when undertaken with guidance from a healthcare professional. Even if you're eating fewer calories, it's important to keep your diet balanced so you get all the nutrients you need.

Examples of Fad Diets

1. Keto diet

What is it? The ketogenic or 'keto' diet focuses on consuming high amounts of fat, moderate protein, and very low carbohydrates.

Promise: By doing this, the body is forced to burn fats instead of carbs, leading to rapid weight loss.

Note: While some people have found success with the keto diet, it's not suitable for everyone. Always consult with a healthcare professional before starting.

2. Paleo diet

What is it? The Paleo diet is inspired by what our ancient ancestors might have eaten. It emphasizes natural foods like meat, fish, nuts, and fruits while excluding processed foods, grains, and dairy.

Promise: Advocates believe that by eating like our ancestors, we can achieve better health and weight loss.

Note: It's worth noting that there's debate about what our ancestors truly ate and if this diet is a precise reflection of that.

3. Atkins diet

What is it? Similar to the keto diet, the Atkins diet is a low-carbohydrate eating plan. It restricts carbs and emphasizes protein and fat as the primary sources of dietary calories.

Promise: The goal is to change your body's metabolism so that you burn fat for energy instead of carbohydrates, leading to weight loss.

Note: Like other fad diets, it's essential to research and consult with a healthcare expert before starting the Atkins diet.

Benefits of a Low-Calorie Diet

Weight loss: Consuming fewer calories than your body uses naturally leads to weight loss. It's a simple equation: when you eat less and burn more, your body turns to stored fat for energy.

Improved blood sugar control: A balanced low-calorie diet can help regulate blood sugar levels, beneficial for people with diabetes or at risk for diabetes.

Reduced risk of heart disease: Eating fewer calories while maintaining a balanced diet can lead to lower cholesterol and blood pressure, reducing the risk of heart disease.

Reduced risk of stroke: A healthier diet and weight can also reduce the risk of strokes by maintaining good blood flow and preventing blockages.

Risks of a Low-Calorie Diet

However, like all diets, there are potential risks to be aware of:

Nutrient deficiencies: If not done carefully, a low-calorie diet might not provide all the necessary nutrients the body needs.

Fatigue: Consuming fewer calories can lead to reduced energy levels, making you feel tired more quickly.

Irritability: A sudden drop in calorie intake can affect mood and lead to irritability.

Dizziness: Not getting enough calories might cause dizziness or lightheadedness.

Hair loss: Severe calorie restriction can lead to hair loss because the body might not get the essential nutrients for hair growth.


In this article, we've explained how is a fad diet different than a low calorie diet? While fad diets promise quick weight loss, they often don't work well and can be unhealthy. Instead, it's better to focus on a balanced approach, like eating fewer calories overall. Just make sure you're still getting all the nutrients you need, even with fewer calories.

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