The calculator calculates your daily protein, fat, carbohydrate and total energy needs. You can set your goal to lose weight, gain weight or maintain weight.
Weight loss is based on energy balance: when you consume more than you eat, your weight decreases. A suitable calorie deficit is 500 kilocalories per day, which will result in a weight loss of about half a kilo per week. Adequate protein intake and exercise will help maintain muscle mass and keep weight under control even after losing weight.
Weight loss or weight gain happens because of changes in the body’s energy balance. Our body needs a certain amount of energy to function and to perform all required tasks, which means it constantly uses energy. Food gives us energy that the body can use. If the energy from food does not meet the body’s energy needs, the remaining energy must come from somewhere else. In this situation, the body can use fat stores or muscle mass, which leads to weight loss. If the energy from food is higher than what the body needs, the extra energy is stored mainly as body fat.
If you want to lose weight, you need to use more energy than you eat. A person’s total energy expenditure consists of basal metabolic rate and daily physical activity. You can estimate your own energy expenditure with our BMR calculator. If the calculator value were completely accurate and you ate fewer calories than that value, your weight would decrease. A common recommendation for weight loss is to eat 500–700 kilocalories less than your daily energy expenditure. This calorie deficit aims for a weight loss of 0.5–1 kilogram per week. Very low-calorie diets may also work for short-term weight loss, especially in people with more body fat. However, a 500-kilocalorie deficit is a good starting point for most people. Unfortunately weight loss is not always that simple, because the body changes during weight loss and energy expenditure may also decrease. A lower energy expenditure can be caused by reduced activity, lower energy needs for digestion, hormonal changes, and adaptation to lower energy intake.
During a long weight-loss process, it can be useful to reassess your energy expenditure and diet. Tracking your body weight can help you evaluate whether you should decrease your calorie intake or increase your activity. However, many factors besides fat loss can affect weight. Not all weight loss comes from the waistline. At the beginning of a diet, body weight often drops quickly; this is usually caused by a reduction in the amount of water stored in the body. If the diet is low in carbohydrates, weight may drop even faster, because carbohydrates are stored as glycogen, which binds about 3–4 grams of water per gram of carbohydrate. A low-carbohydrate diet may therefore seem effective for some people, as rapid changes can increase motivation. When adopting healthier lifestyle habits and especially when increasing strength training, it is also possible to gain muscle mass. This can slow down weight loss even if fat mass is decreasing.
After weight loss, it is very common for weight to return to the starting level or even higher. Maintaining weight after a diet can be even more difficult than losing the weight. Research shows that a higher protein intake helps prevent weight regain. Protein helps with satiety, and the feeling of fullness from protein is stronger compared to other macronutrients.
As mentioned, a higher protein intake can help with weight maintenance. Adequate protein intake is also important during weight loss. Protein needs vary between individuals, and the amount needed depends on age, activity level, and personal goals. The minimum protein requirement is 0.8 grams per kilogram of body weight. However, this is not an “optimal” amount, but simply the amount needed to avoid deficiency. When considering aging and the natural loss of muscle mass, intakes of ≥ 1.2 g/kg are associated with less muscle loss. If the goal is to maximize muscle growth, it may be better to aim for 1.6–2.2 g/kg. Higher intakes have also been studied, and people in a calorie deficit may benefit from 2.3–3.1 g/kg to maintain muscle mass.
Many nutrition guidelines recommend that 20–35% of daily energy intake should come from fat. This helps ensure adequate intake of essential fatty acids and fat-soluble vitamins. For someone eating 2000 kilocalories per day, this equals about 44–78 grams of fat. The recommended intake of carbohydrates is 45–65% of daily energy. In practice, carbohydrates function as the main energy source in the body. Carbohydrates are not considered essential nutrients like protein and fat, because the body can synthesize carbohydrates and use other nutrients as energy sources.
Changes in body weight are based on energy balance, but many people also want to change their body composition. This means increasing or maintaining muscle mass and reducing fat mass, which leads to a lower body fat percentage and a different body composition. From a health perspective, it is also important to maintain muscle mass during weight loss. Higher muscle mass is also linked to lower overall mortality in older adults. For muscle mass and strength, it is important to include strength training in your weekly routine. The World Health Organization guidelines on physical activity recommend doing strength and balance training twice per week for adults.
Endurance-type exercise has been shown to support weight-loss outcomes. Especially when doing 2.5 hours of endurance exercise per week, there is a positive effect on weight reduction and a decrease in waist circumference. The positive effects are even greater when endurance exercise is done for five hours per week. The World Health Organization guidelines on physical activity recommend at least 2.5 hours of moderate-intensity endurance exercise per week.
Published: 26.09.2025
Updated: 18.12.2025
Lassi Honkanen
physiotherapist
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