Read the guide · Nutrition
How Letz sets your nutrition target
The target begins with the Mifflin-St Jeor equation and an activity factor, and is replaced by adaptive expenditure once there are weeks of logged weight and intake. The deficit or surplus is a fraction of expenditure, protein is calculated per kilogram and distributed across meals, fat has a floor, and carbohydrate is the macro that increases on training days. The ranges below are the same ones used in the code.
Numbers derived from this rule
| Parameter | Range | Weight | Rule |
|---|---|---|---|
| Calorie deficit | 10–25 % of expenditure1 variant by context | 80% | Deficit of 10 to 25% of expenditure, aiming for a loss of 0.5 to 1% of body weight per week; faster rates cost lean mass and metabolism.Rate of weight loss · Higher Protein Intake During a Calorie Deficit · Weight change is dynamic |
| Weekly weight change | 0.5–1 % of body weight/week1 variant by context | 60% | Lose 0.5 to 1% of body weight per week; gain up to about 0.5% per week when the goal is mass.Rate of weight loss · Calorie surplus for muscle gain |
| Daily protein | 1.6–2.2 g/kg/day2 variants by context | 90% | 1.6 to 2.2 g/kg/day for those who train; in a deficit, the upper end of the range protects lean mass.Protein and Training Adaptation · Higher Protein Intake During a Calorie Deficit |
| Protein per meal | 0.3–0.55 g/kg/meal | 50% | About 0.4 g/kg per meal across four or more meals maximizes protein synthesis; older adults need the upper end of the range.Distribute protein throughout the day · Protein in older adults |
| Protein meals per day | 3–5 meals | 40% | The number of meals does not affect weight; distributing protein across 3 to 5 meals improves its utilization.Distribute protein throughout the day · Nutrient timing and the anabolic window · Meal Frequency and Eating Window |
| Fiber | 12–16 g per 1000 kcal | 50% | About 14 g of fiber per 1000 kcal, which amounts to 25 to 29 g per day for most adults.Fiber and Carbohydrate Quality · Ultra-Processed Foods Lead to Eating More |
| Diet break after | 6–12 weeks in a deficit | 20% | After 6 to 12 weeks in a deficit, one or two weeks at maintenance reduce hunger and adaptation without gaining fat.Planned Diet Breaks · Weight Loss Maintenance and Metabolic Adaptation |
Rules and studies
- 01Estimating energy expenditureThe Mifflin-St Jeor equation is the most accurate formula for estimating resting energy expenditure, but it still errs in a significant portion of individuals.The initial target uses Mifflin-St Jeor with an activity factor and is replaced by adaptive TDEE as soon as there is sufficient weight and intake data.
- 02Weight change is dynamicThe body's weight response to sustained changes in energy intake is gradual and involves adaptations; projections should use curves and ranges rather than a rigid linear rule.The weight forecast in Progress uses the observed trend and an uncertainty range, never a promised target date.
- 03Rate of weight lossLosing weight slowly, at around 0.5 to 1% of body weight per week, better preserves lean mass, strength, and metabolic rate compared to rapid weight loss.The default calorie deficit in Letz is 15% of energy expenditure, capped between 250 and 500 kcal, and weight forecasting uses ranges rather than a promised date.
- 04Protein and Training AdaptationSufficient protein can support gains in lean mass and strength alongside training; the response varies and does not increase indefinitely with higher intakes.The Letz protein target uses 1.6 to 2.2 g/kg depending on the goal, calculated using whichever is lower between current weight and target weight.
- 05Higher Protein Intake During a Calorie DeficitIn a deficit, higher protein protects lean mass and can even allow muscle gain alongside intense training; the effective range rises to approximately 1.6 to 2.4 g/kg.Weight loss and recomposition goals default to 1.8 g/kg and allow up to 2.4 g/kg when the coach adjusts the strategy.
- 06Distribute protein throughout the dayDividing protein into servings of around 0.4 g/kg across four or more meals stimulates protein synthesis more than concentrating everything into one or two.The meal plan distributes protein evenly across planned meals instead of clustering it all at dinner.
- 07Fiber and Carbohydrate QualityConsuming 25 to 29 g of fiber per day, alongside whole grains, is associated with lower mortality and fewer cardiometabolic diseases.The Letz fiber target is 14 g per 1000 kcal, between 20 and 50 g, and the meal plan prioritizes whole-food sources.
- 08Diet Type Matters Less Than AdherencePopular named diets lead to similar weight loss; adherence to the plan predicts outcomes far more than the ratio of carbohydrates to fat.The meal plan is built around foods the person already enjoys, logs dislikes and restrictions, and does not impose a single rigid pattern.
- 09Weight Loss Maintenance and Metabolic AdaptationEnergy expenditure drops more than expected after weight loss and appetite increases; maintaining weight requires continuous monitoring, high physical activity levels, and a consistent eating pattern.Upon reaching a goal weight, Letz suggests transitioning to maintenance with targets, steps, and weigh-ins instead of simply ending the plan.