← All guides

Build muscle week by week

Guides · Start with your goal · Muscle gain

Muscle is built a little at a time: steady training that asks a bit more of you, and enough food every day to build with. Most people find the gym the easy half. This guide covers the short science, the part that usually trips people up, and how Strathlon helps you eat for the training you're doing.

Before you start: this is general fitness education, not medical or dietary advice. If you have a health condition, are pregnant or breastfeeding, or have a history of disordered eating, speak to a qualified professional before changing how you eat or train.

On this page

  1. The science, briefly
  2. What gets in the way
  3. How Strathlon helps you eat enough
  4. Use your numbers to decide
  5. Your sport, and where to read more
  6. Staying safe
  7. References

1. The science, briefly

  • Muscle grows when training asks a little more over time. That can mean more weight, more reps or better control, with enough rest to recover between sessions.[1][2] This is called progressive overload, and your plan's sessions are built around it.
  • A small surplus is enough. Eating slightly more than you use gives new muscle the energy it needs. A big surplus doesn't build muscle any faster; most of the extra ends up as fat.[3][4] Strathlon sets your calories a little above maintenance: about 200 kcal more on rest days and about 300 kcal more on training days.
  • Protein is the building material. Most guidance for building muscle puts protein at about 1.6 to 2.2 g per kg of body weight a day.[5] Strathlon sets yours just above that range, at 2.3 g per kg (worked out from a healthier reference weight if you are carrying a lot of extra weight).
  • It's slow, and slower with experience. A pace often recommended for newer lifters is about 0.25 to 0.5% of body weight a week, and gains slow down as you become more experienced.[6] Some of what the scale shows early on is water and stored carbohydrate rather than muscle.[7]

2. What gets in the way

For many people building muscle, the hard part isn't the training. It is eating enough, every day, protein included. Eating more than usual, every day, is harder than it sounds: a review of weight-gain advice for athletes notes that the recommended gain can be difficult for some to reach.[8] Busy days, skipped breakfasts and meals eaten on the move make it easy to fall short without noticing, and a week of small shortfalls quietly cancels the surplus.

3. How Strathlon helps you eat enough

The quicker a meal is to log, the more likely you are to see a shortfall in time to fix it. Most of this starts on the AI Coach tab.

  • Food from a pack. Photograph the pack with its barcode showing and Strathlon fills in the pack's own figures from Open Food Facts, a free public database of food labels. No match? Tap Photograph the label and it reads the printed panel.
  • A meal on a plate. Photograph it, or type what you ate, and you get an estimate of calories, protein, carbs and fat. A few words with the photo make the estimate closer.
  • Left some? Tap I didn't finish this, describe or photograph what's left, and the coach works out what you actually ate.
  • Protein in view. The Tracker shows protein, carbs and fat bars beside your calories, so by mid-afternoon you can see whether you're on course, and add a protein-rich snack while there's still time.

Photo logging, barcode and label reading, describing a meal to the coach and the leftovers fix are part of the AI Coach subscription. Without it you can still type your day's calories into the Tracker yourself.

4. Use your numbers to decide

  • Extra session, long walk, a game of five-a-side? On the Plan tab, tap Add activity and log it. Your target for the day rises by the app's estimate, so you know how much more to eat to keep your surplus. An activity you log counts in full on that day.
  • Check your lifts, not just the scale. On Progress, the Strength history tile calls your lifting Improving, Holding or Declining over the last 12 weeks. Weight and lifts rising together is the sign the plan is working.
  • Weight flat for a few weeks and lifts stuck? You may be eating less than you think: most people under-record what they eat.[9] Tighten your logging for a week before changing anything else.

5. Your sport, and where to read more

If you play a sport and picked Sports Performance as your second goal, your plan runs a slight surplus with extra carbohydrate around match days. If you've ticked the days you play, the Nutrition tab also gives you advice for before and after a match and the evening before.

Want the detail? These go deeper:

6. Staying safe

  • Under 18, or your answers to the food questions in setup suggest care is needed? The app keeps your calories at maintenance rather than a surplus, alongside your strength training.
  • Pregnant or breastfeeding? The app sets no calorie target at all and asks you to follow your midwife's or doctor's guidance on eating.

None of this replaces medical advice. If you have a health condition, or you're unsure whether a plan is safe for you, speak to your GP or a registered dietitian first.

References

The figures in this guide come from the sources below. Where a number reflects a professional body's guidance, the citation names that body and its country. Facts about how Strathlon works come from the app itself.

  1. American College of Sports Medicine (ACSM, United States) position stand. Progression models in resistance training for healthy adults. Medicine & Science in Sports & Exercise. 2009;41(3):687–708. Progressive protocols are needed to keep stimulating adaptation. PubMed 19204579
  2. Plotkin D, Coleman M, Van Every D, et al. Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. PeerJ. 2022;10:e14142. Adding load or adding reps both produced similar muscle growth. PubMed 36199287
  3. Helms ER, Spence AJ, Sousa C, et al. Effect of small and large energy surpluses on strength, muscle, and skinfold thickness in resistance-trained individuals: a parallel groups design. Sports Medicine – Open. 2023;9(1):102. PMC10620361
  4. Slater GJ, Dieter BP, Marsh DJ, Helms ER, Shaw G, Iraki J. Is an energy surplus required to maximize skeletal muscle hypertrophy associated with resistance training? Frontiers in Nutrition. 2019;6:131. PMC6710320
  5. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52(6):376–384. No further gains beyond about 1.6 g/kg/day, with the upper confidence limit at about 2.2 g/kg. PubMed 28698222
  6. Iraki J, Fitschen P, Espinar S, Helms E. Nutrition recommendations for bodybuilders in the off-season: a narrative review. Sports (Basel). 2019;7(7):154. Recommends about 0.25–0.5% of body weight a week for novice-to-intermediate lifters and notes growth slows with experience. PMC6680710
  7. Fernández-Elías VE, Ortega JF, Nelson RK, Mora-Rodriguez R. Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. European Journal of Applied Physiology. 2015;115(9):1919–1926. Each gram of glycogen is stored with at least 3 g of water. PubMed 25911631
  8. Larson-Meyer DE, Krason RK, Meyer LM. Weight gain recommendations for athletes and military personnel: a critical review of the evidence. Current Nutrition Reports. 2022;11(2):225–239. Appetite is a genuine limit on achieving a surplus. PubMed 35233712
  9. Freedman LS, Commins JM, Moler JE, et al. Pooled results from 5 validation studies of dietary self-report instruments using recovery biomarkers for energy and protein intake. American Journal of Epidemiology. 2014;180(2):172–188. PubMed 24918187

This is general educational information rather than medical, dietary or coaching advice. Figures are population-level guides from published research, and individual results vary. Anyone with a health condition, a history of disordered eating, or who is pregnant or postpartum should consult a qualified physician or registered dietitian before starting or changing an exercise or nutrition programme. See our Terms for more.

← All guides · Lose fat · Build muscle · Get fitter · Fuel your sport · Help · Home