カロリー計算機
年齢・体重・身長・活動量に基づく1日のカロリー需要を計算
使い方
- Select your sex (biological).
- Enter your age, weight (kg), and height (cm).
- Select your activity level — how often you exercise per week.
- Your TDEE (Total Daily Energy Expenditure) is calculated using the Mifflin-St Jeor equation.
計算式
TDEE = BMR × Activity Factor (1.2–1.9)
W = weight (kg), H = height (cm), A = age (years)
Why Calorie Counting Works: The Science of Energy Balance
At its core, body weight is governed by the energy balance equation: calories consumed minus calories burned. When intake exceeds expenditure (a caloric surplus), the body stores the excess as glycogen and adipose tissue. When expenditure exceeds intake (a caloric deficit), stored energy is mobilised—primarily from fat tissue. This is one of the most robustly established principles in nutrition science, supported by metabolic ward studies and decades of controlled trials.
That said, the body is not a simple furnace—hormones, gut microbiome composition, meal timing, macronutrient ratios, and individual metabolic variation all influence how efficiently calories are used and stored. For optimal results, calorie targets should be combined with food quality awareness, adequate protein intake, and regular exercise. The CDC's guide to healthy weight and nutrition and the Wikipedia article on calorie restriction provide balanced overviews of the evidence.
Calories by Goal: How Much Should You Actually Eat?
Macronutrients: Building Your Calorie Budget
Reaching your calorie goal is necessary but not sufficient—the source of those calories shapes body composition, energy levels, and long-term adherence:
🫒 Fats (9 kcal/g): 20–35% of total calories. Essential for hormones (testosterone, estrogen), fat-soluble vitamins (A, D, E, K), and brain health.
🍚 Carbohydrates (4 kcal/g): Remaining calories. Primary fuel for high-intensity exercise, glycogen stores, and cognitive function. Prioritise whole food sources.
How to Use This Calculator Effectively
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), then multiplies by an activity factor to estimate your maintenance calories (TDEE). From there, it projects weight-loss and weight-gain calorie targets.
For best results: (1) be honest about your activity level—most people overestimate it; (2) track your food intake for 2–4 weeks alongside the calculated target and adjust if weight is not changing as expected; (3) recalculate every 4–8 weeks as your weight changes, because your maintenance calorie needs shift. Pair this with our 1日の総消費カロリー計算機 for a detailed activity breakdown and our BMI計算機 to track your weight status over time.
Frequently Asked Questions About Calories
How many calories should I eat to lose weight?
A sustainable rate of fat loss is 0.5–0.75 kg per week, which requires a daily caloric deficit of approximately 500–750 kcal. For most adults, this means eating 1,400–1,800 kcal/day depending on their size and activity. Very low calorie diets (<1,200 kcal for women, <1,500 for men) can impair metabolic health and should only be followed under medical supervision.
What is the best diet for weight loss—low carb or low fat?
Long-term randomised controlled trials show that both low-carbohydrate and low-fat diets produce similar weight loss outcomes when calorie intake and protein are matched. The best diet is the one you can adhere to consistently. Individual responses to carb vs. fat restriction vary significantly based on insulin sensitivity and personal preference.
Do I need to count calories to lose weight?
Not necessarily. Many people lose weight through mindful eating, portion control, food quality improvements, and increasing protein intake—without explicitly tracking calories. However, research consistently shows that calorie awareness significantly improves outcomes, particularly when used for a defined period to calibrate portion sizes and food choices.
Why do I stop losing weight even in a calorie deficit?
Two primary reasons: (1) Metabolic adaptation—your body reduces BMR in response to sustained caloric restriction. (2) Tracking errors—research shows people underestimate calorie intake by 20–50% on average. Recalculate your TDEE based on your current weight, consider a one-week diet break at maintenance, and tighten tracking accuracy.
Related Health Calculators
References & Further Reading
- Hall KD, et al. Energy balance and its components: implications for body weight regulation. Am J Clin Nutr, 2012.
- Wikipedia contributors. Calorie Restriction. Wikipedia, The Free Encyclopedia.
- CDC. Healthy Weight, Nutrition, and Physical Activity. CDC, 2024.
- Sacks FM, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. NEJM, 2009.