Which Diet Works Best?
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Introduction
Losing weight is a common goal for many people, but choosing the right diet can be confusing. Two popular options are intermittent fasting (IF) and calorie restriction (CER). Both have been shown to help with weight loss and improving health, but which one is more effective?
A recent review of 167 studies involving nearly 12,000 adults looked at different types of fasting and calorie-cutting diets. It compared how well they worked for weight loss and improving blood pressure, cholesterol, and blood sugar levels. Let’s break down what the research found in simple terms.
What Are Intermittent Fasting and Calorie Restriction?
Calorie restriction (CER) is when you eat fewer calories every day. This can be done in different levels:
- Mild: Eating slightly less (around 1500–2000 calories a day)
- Moderate: Eating much less (about 880–1500 calories)
- Severe: Very low intake (less than 880 calories daily)
Intermittent fasting (IF) is when you alternate between eating and fasting. Common types include:
- Time-Restricted Eating (TRE): Eat during a specific window, like 8 hours a day
- 5:2 Diet: Eat normally for 5 days and fast for 2 days a week
- Alternate-Day Fasting (ADF): Fast every other day
- Periodic Fasting: Fast for several days in a row, then eat normally
Which Diet Helps You Lose More Weight?
The study found that cutting more calories leads to more weight loss, no matter the method.
- Severe CER helped people lose the most—around 11.5 kg
- ADF led to about 5 kg of weight loss
- Moderate CER helped people lose around 6 kg
- TRE and 5:2 diets resulted in about 4–5 kg lost, similar to mild CER
So, both IF and CER work, but the amount of calorie reduction matters most.
Do These Diets Improve Health?
Besides weight loss, the study looked at:
- Blood pressure
- Cholesterol and triglycerides
- Blood sugar levels
Findings:
- Severe CER showed the most improvement in all areas
- ADF and periodic fasting also helped with blood pressure and cholesterol
- TRE and 5:2 diets had smaller effects
This means stricter diets bring more health benefits, but they may be harder to follow.
Are These Diets Easy to Follow?
Not always. In fact:
- ADF had the highest dropout rate, meaning more people gave up
- Surprisingly, severe CER had fewer dropouts, possibly because people got more support (like help from dietitians)
Also, people doing IF often started regaining weight after 12 weeks. CER diets seemed better for long-term results.
What’s the Best Diet for You?
Here’s what to keep in mind:
- Pick a plan you can stick with
- If you like structure and meal tracking, try calorie restriction
- If you want flexibility, intermittent fasting may suit you better
- Any diet works better with support—like apps, friends, or a professional
Final Thoughts
Both intermittent fasting and calorie restriction can help you lose weight and improve your health. But the biggest factor is how much you reduce your calorie intake, not when you eat. Choose the plan that fits your lifestyle and makes you feel good—that’s the one you’re most likely to stick with.