How do calories work on Reddit and other fitness forums?

November 16, 2025 •

4 min read

According to years of discussions across Reddit, the core principle of weight management remains 'calories in vs. calories out' (CICO). This approach, foundational to how calories work on Reddit and other online forums, emphasizes that weight loss occurs when you consume fewer calories than your body burns.

Quick Summary

This guide explores how calories and CICO are understood within Reddit's fitness and nutrition communities, highlighting popular tracking tools, calculation methods, and community-driven advice. The content differentiates between factual information and common misconceptions to help users make informed decisions for their health goals.

Key Points

CICO is King: The foundational principle on Reddit for weight change is the 'calories in, calories out' (CICO) model, where a deficit causes weight loss and a surplus causes weight gain.
Start with TDEE: Redditors advise calculating your Total Daily Energy Expenditure (TDEE) to find your maintenance calories and then creating a deficit for weight loss.
Use a Digital Scale: Accurate tracking is key, and the Reddit community strongly recommends using a digital food scale to avoid inaccuracies from eyeballing portion sizes.
Choose the Right App: Popular calorie tracking apps recommended on Reddit include Cronometer, MacroFactor, Lose It!, and MyFitnessPal, each with pros and cons regarding database accuracy and features.
Expect Inaccuracies: Many Redditors acknowledge that exercise trackers and food labels are only estimates, so consistent tracking and adjustments based on weight trends are more important than daily precision.
Be Mindful of Myths: The community actively debunks myths like 'CICO is a myth,' 'not all calories are equal for weight loss,' and 'exercise burns off everything,' providing a reality check for newcomers.
Listen to Your Body: Ultimately, the Reddit advice emphasizes that tracking is a tool for awareness, and adjusting based on your body's feedback is the most reliable long-term strategy.

Understanding the Core Principle: CICO and TDEE

The most widely accepted and consistently repeated concept across Reddit's numerous fitness and weight-loss subreddits is the energy balance equation: Calories In, Calories Out (CICO). At its heart, this principle states that weight is gained when you consume more energy (calories) than your body expends, and lost when you consume less. This basic law of thermodynamics is universally upheld, though some discussions explore its nuances.

Central to the CICO model is your Total Daily Energy Expenditure (TDEE). This number is the total amount of energy your body burns in a day and is composed of several factors:

Basal Metabolic Rate (BMR): The energy required to keep your body functioning at rest.
Thermic Effect of Food (TEF): The energy used to digest and process food.
Activity Level: The energy burned through exercise and other movement.

How Redditors Calculate and Track Calories

Unlike traditional health platforms, Reddit's approach to calorie management is a blend of personal experience, crowd-sourced tips, and reliance on dedicated tracking applications. Newcomers are often directed to several key steps:

Estimate TDEE: Users are encouraged to start with a reliable online TDEE calculator, inputting their age, weight, height, and activity level. Many subreddit guides, like those in r/loseit, advise new trackers to set their activity level to 'sedentary' for a more conservative estimate.
Choose a Tracking App: The Reddit community consistently recommends a handful of calorie-counting apps. Apps like MyFitnessPal, Lose It!, and Cronometer are repeatedly cited for their comprehensive food databases and tracking capabilities.
Weigh Everything: One of the most critical pieces of advice, emphasized to ensure accuracy, is to use a digital food scale. Redditors stress that eyeballing portions is a common cause of stalled progress, and weighing your food is the most reliable way to know your true caloric intake.
Adjust Over Time: The TDEE calculators and app recommendations provide a starting point. Veteran Redditors consistently advise new members to monitor their weekly weight trends and adjust their caloric intake accordingly, acknowledging that individual metabolism varies and estimates are not perfect.

Common Reddit Calorie Myths and Facts

Subreddits like r/loseit and r/nutrition frequently address and debunk misinformation surrounding calories. The collective knowledge of these communities helps newcomers navigate a confusing topic.

Myth: The concept of CICO is a myth.

Fact: The law of conservation of energy states that energy cannot be created or destroyed, only converted. The human body is subject to this principle. While the body's metabolic efficiency can vary, a consistent calorie deficit will result in weight loss. Those who claim CICO 'doesn't work' are often underestimating their intake or overestimating their expenditure.

Myth: Not all calories are equal.

Fact: From a purely thermodynamic standpoint for weight change, a calorie is a calorie. However, this statement is misleading. The source of those calories matters immensely for satiety, nutrition, and overall health. For example, 500 calories from a bag of chips will leave you feeling much different than 500 calories from chicken breast and vegetables. Redditors stress focusing on nutrient-dense foods to feel full and stay within calorie goals.

Myth: Exercise will burn off your excess calories.

Fact: While exercise is crucial for overall health and can contribute to weight loss, its caloric impact is often overestimated. Counting 'calories burned' on gym machines or smartwatches can be notoriously inaccurate, and the additional calories are often minimal compared to a full day's intake. Experienced Redditors suggest focusing on diet first and using exercise as a way to increase health and potentially a small caloric cushion.

Comparison of Common Calorie Tracking Apps Mentioned on Reddit


Feature	MyFitnessPal	Cronometer	Lose It!	MacroFactor
Database Size	Very large, but can have many user-submitted, inaccurate entries.	Verified, accurate database.	Reputable, user-friendly database.	High-quality database with minimal user error.
Cost	Free version available, paid premium for advanced features.	Free and paid version available.	Free and paid version available.	Paid subscription only.
Unique Features	Strong community aspect and large food database.	Excellent micronutrient tracking and detailed reports.	Focuses heavily on user experience and motivation tools.	Calculates and dynamically adjusts TDEE and calorie goals weekly.
Accuracy	Can be unreliable due to user-generated data, requiring careful manual verification.	Highly accurate due to curated database.	Generally reliable, similar to MyFitnessPal with a cleaner interface.	Extremely accurate for determining TDEE over time due to intelligent algorithms.
User Sentiment on Reddit	Praised for its large database, criticized for data accuracy and intrusive ads.	Highly recommended for detail-oriented users who want accurate micronutrient info.	Well-regarded for its simplicity and supportive community.	Praised for its accurate TDEE adjustment and lack of adherence-shaming.

Conclusion: Sifting Through the Advice

Navigating calorie advice on Reddit requires a discerning eye, but the community provides a wealth of practical and supportive information. The core consensus remains that calorie counting, driven by the CICO principle and an accurate TDEE estimate, is a reliable method for managing weight. By using a digital food scale, sticking with a highly recommended app like Cronometer or MacroFactor, and focusing on consistency over perfection, Redditors find success. While the platform can be a powerful tool for peer support and motivation, it's crucial to filter out myths and remember that for individual health concerns, professional medical advice is always the most reliable source. The community acts as a valuable resource for strategy and accountability, not as a replacement for expert guidance.

For more scientifically grounded insights on the human body's energy balance, you can consult authoritative health sites. One example is the paper on AI-Powered analysis of weight loss from Reddit by MDPI, which offers a broader perspective on dietary research through social media data.

Frequently Asked Questions

On Reddit, CICO stands for 'Calories In, Calories Out,' which refers to the fundamental principle of energy balance. A calorie deficit (eating less than you burn) leads to weight loss, and a surplus leads to weight gain.

A TDEE (Total Daily Energy Expenditure) calculator is an online tool that estimates how many calories your body burns in a day, based on your age, weight, height, and activity level. Redditors recommend it as a starting point to determine your baseline calorie needs for weight management.

While Reddit's community can provide a wealth of supportive and anecdotal advice, the reliability of information can vary. The core principles like CICO are sound, but it is important to critically evaluate individual user claims and remember that it is not a substitute for professional medical or nutritional guidance.

The most accurate calorie counting method, as advised on Reddit, involves using a digital food scale. Apps and eyeballing portions can be inaccurate, and weighing your food is the most reliable way to ensure you are meeting your intake goals consistently.

Based on widespread discussion, some of the most recommended calorie tracking apps on Reddit include Cronometer, MacroFactor, Lose It!, and MyFitnessPal, each offering different features and levels of database accuracy.

Experienced Reddit users often recommend not 'eating back' calories burned according to fitness trackers because they are notoriously inaccurate. Instead, they focus on a consistent diet and treat exercise as an added benefit rather than a direct calorie buffer.

Many users advise setting your activity level to sedentary on TDEE calculators to get a more conservative, and often more accurate, baseline calorie target. This approach prevents overestimating calories burned and ensures that any exercise-related weight loss is a bonus rather than a requirement.