The surprising truth: Sometimes eating more calories helps with weight loss
Many people trying to lose weight cut their calorie intake dramatically — I often hear from people who say they’re eating around 1,000 calories per day and aren’t seeing any progress. In this article “calories” refers to kilocalories (kcal), the standard unit used to measure the energy in food.
That may sound counterintuitive: how could consuming more calories ever help you lose weight? The short answer is that the body’s response to very low calorie intake can slow metabolism, reduce energy, and make sustainable weight loss harder. Read on to learn how to estimate your daily caloric needs, adjust calorie intake safely, and use food and activity to support lasting weight loss.
Why calories matter: what your body uses energy for
Your body needs energy — measured in kilocalories (kcal) and commonly called “calories” — to function every day. Calories fuel breathing, circulation, digestion, thinking, walking, and exercise. That energy requirement is your daily calorie need and it varies by age, sex, height, muscle mass, and activity level.
Health organizations and registered dietitians often use a general lower limit of about 1,200 kcal per day for many adults as a cautionary floor: consuming fewer than ~1,200 calories per day without medical supervision can make it hard to meet nutrients and may lower metabolic rate. (Individual needs vary; athletes, larger people, and people with more muscle typically need far more energy.)
How energy is burned
- Basal metabolic rate (BMR): the energy your body uses at rest to support breathing, circulation, and core functions.
- Physical activity: calories burned during movement and exercise — this changes most with your daily routine and intentional workouts.
- Thermic effect of food: a small portion of calories are used to digest, absorb, and process nutrients.
Because these components determine how many calories your body needs per day, understanding them helps you set a safe calorie intake for weight loss or weight maintenance. Later in this article you’ll find simple formulas to estimate maintenance calories and practical suggestions to adjust intake for steady weight loss or muscle gain.
How the body handles calories — energy balance, macronutrients, and calculators
When you consume more calories than your body uses, the surplus energy is stored for later use — primarily as body fat, though some surplus protein can support muscle if paired with resistance training. In short: energy balance (calories in versus calories out) determines weight change, regardless of whether those calories come from carbs, fat, or protein.
Energy in vs. energy out
Your body’s daily caloric needs depend on several factors: age, sex, height, current weight, muscle mass, and activity level. These factors together determine your basal metabolic rate (BMR) plus the additional calories burned through physical activity and the thermic effect of food. Understanding these components helps explain why two people eating the same number of calories can have very different results.
- Calories in: the total calorie intake from food and drink each day, including meals and snacks.
- Calories out: BMR (energy to maintain basic life functions) + daily movement/exercise + the energy used to digest food.
Why very low calorie intake can backfire
Using generic online calculators can give you a rough estimate of maintenance calories, but they often include a wide “recommended” range that may be too low for someone who is active or has more muscle. If you consistently eat far below your actual needs — for example, some people report trying to lose weight on ~1,000 kcal per day — your body can adapt by lowering metabolic rate, reducing energy levels, and making exercise feel harder. That metabolic adaptation can stall weight loss and make it harder to lose weight sustainably.
This is why I caution against blindly following the lowest number from a free calorie calculator. Instead, use calculators as a starting point, then monitor changes in weight, energy, and performance, and adjust your calorie intake and activity accordingly.
Practical examples
Example 1 — energy deficit for steady weight loss: If a person’s estimated maintenance is 2,000 calories per day, subtracting about 500 calories per day (a common rule of thumb) creates a weekly deficit of ~3,500 calories, roughly equivalent to 1 pound of weight loss per week. However, if someone’s real maintenance is higher because of muscle mass or activity, the same intake could produce slower loss than expected.
Example 2 — too-low intake and stalled progress: A person who estimates maintenance at 1,400 kcal but then eats 1,000 kcal per day may initially lose weight but could quickly feel fatigued, experience nutrient gaps, and see their resting energy needs decline — making further weight loss difficult and increasing the risk of regaining weight later.
Macronutrients and body composition
While total calories determine weight change, macronutrient composition affects hunger, muscle retention, and how your body partitions energy. Higher protein intake supports muscle retention during weight loss, and strength training helps ensure that weight lost comes more from fat than from muscle.
In short: aim for a reasonable calorie intake that creates a moderate deficit (if your goal is weight loss), prioritize protein and whole foods over processed foods and added sugar, and include resistance exercise to protect muscle. Monitor your results and adjust based on how your body responds — numbers from calculators are a starting point, not a final verdict.
Practical targets and quick formulas to estimate maintenance and set goals
A common, practical approach is to first estimate your maintenance calories, then adjust from there. For steady weight loss, many people subtract about 500 calories per day from maintenance — this typically produces roughly 1 pound of weight loss per week (a 3,500 kcal weekly deficit). However, don’t reduce your intake below levels where you risk nutrient shortfalls or excessive fatigue; many clinicians use ~1,200 kcal per day as a general lower bound for most adults, but individual needs vary and you should consult a healthcare provider before going lower.
If your goal is to gain muscle, add about 300 calories per day to your maintenance estimate and prioritize a structured resistance training program; the extra energy helps support muscle gain while the strength training provides the stimulus to build muscle rather than store excess as fat.
Simple maintenance multipliers
One quick way to estimate maintenance calories is to multiply your current weight (in pounds) by an activity-based factor. These are rough estimates that give you a starting point for setting calorie intake:
- Inactive lifestyle (sedentary, desk job): Current weight (lbs) × 12 = estimated maintenance calories per day.
- Moderately active (light daily movement or standing job): Current weight (lbs) × 13 = estimated maintenance calories per day.
- Highly active (manual labor or high daily activity): Current weight (lbs) × 14 = estimated maintenance calories per day.
Worked examples
Example — weight loss: A 160-lb person with a moderately active lifestyle: 160 × 13 = 2,080 kcal estimated maintenance. Subtract ~500 kcal → target ≈ 1,580 kcal/day to aim for about 1 lb/week of loss. Monitor energy, performance, and weekly weight change — if weight stalls after a few weeks, reassess activity, portions, or consult a professional.
Example — muscle gain: The same 160-lb moderately active person who wants to add muscle could set maintenance at 2,080 kcal and add ~300 kcal → target ≈ 2,380 kcal/day while following a progressive resistance training routine to maximize muscle gain and minimize fat gain.
Convert to metric and customize
To convert the multipliers for kilograms, multiply the maintenance estimate by 2.2 (or use: kg × 27–31 depending on activity). For example, a 73-kg moderately active person (73 × 13 × 2.2/2.2 equivalence) would follow the same calorie target logic. Remember that these multipliers are approximate — many factors (age, sex, body composition, hormones, medications, and fitness level) influence daily caloric needs.
Safety note: if you have medical conditions, are pregnant, breastfeeding, or have a history of disordered eating, work with a registered dietitian or medical provider to determine safe calorie targets. Use these quick formulas as starting points, then adjust based on monitored results (weight trend, energy, strength performance, and how your clothes fit).
Next steps: use the maintenance estimate to set a realistic calorie intake, prioritize whole foods and adequate protein, schedule regular physical activity including resistance exercise, and reassess your caloric intake every 2–4 weeks until you find a sustainable plan that supports your health and goals.
In summary: Estimate your maintenance calories, then create a moderate, sustainable plan based on that number — for many people a 500-calorie-per-day deficit produces steady weight loss (roughly 1 lb per week), while adding ~300 calories with proper resistance training supports muscle gain. Avoid prolonged intake below about 1,200 kcal per day without medical supervision; individual daily caloric needs vary with age, sex, body composition, and activity level.
Focus on whole foods, adequate protein, and consistent physical activity to protect muscle and support health. Monitor your weight trend, energy, and performance for several weeks and adjust calorie intake and exercise as needed.
Next steps: try a maintenance-calorie calculator to get a personalized starting point, plan meals that prioritize nutrient-dense foods over processed foods and added sugar, and if you have medical concerns or complex goals, consult a registered dietitian or healthcare provider.
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