100 kg to 70 kg: projected effects of your plan
This is not a medical assessment. It is an estimate built from your numbers and published research, written in the style of a clinical report. Take it to your GP before starting, and have them check you while you follow the plan.
01Summary
Overall rating: High risk. The goal is achievable and losing 30 kg would bring big health benefits. The way this plan gets there is the problem. You would eat a quarter of what you burn while training more than 5 hours a day, much of it under a 20 kg vest. At that gap your body cannot release fat fast enough to cover the shortfall, so a large share of what you lose would be muscle. The risks of gallstones, injury, fainting and hormone disruption are well above normal.
Diet plan 2 (chicken-based, 1,144 kcal, no milk) covers your protein, so you keep more muscle than on diet 1, and it reaches 70 kg in about 105 days (25 Jan 2027). It is still High risk because the daily gap is around 2,750 kcal with very little carbohydrate, fat and calcium. See section 03.
02Daily intake analysis
| Food | Amount | kcal | Protein | Carbs | Fat* |
|---|---|---|---|---|---|
| Milk (standard) | 50 ml | 32 | 1.7 g | 2.4 g | 1.7 g |
| Rolled oats | 50 g | 200 | 16.9 g† | 33 g | 3.5 g |
| Peanut butter | 30 g | 200 | 10 g | 6 g | 15 g |
| Protein powder (whey) | 60 g | 240 | 48 g | 6 g | 3 g |
| Wattie's vege mix | 320 g | 179 | 6 g | 30 g | 1 g |
| Vitasport electrolyte | 1 pouch | 125 | 0 g | 31 g | 0 g |
| Total | 976 | 82.6 g | 108.4 g | ~24 g |
* Fat is estimated from typical labels; your list didn't include it. † 50 g of rolled oats usually has about 6–7 g of protein, so check this label. Your real protein may be closer to 72 g.
| Nutrient | You get | Needed for this training | Status |
|---|---|---|---|
| Energy | 976 kcal | ~2,800 kcal for a safe pace | Far too low |
| Protein | 72–83 g | ~160 g (1.6 g per kg) | Half of need |
| Carbohydrate | 108 g | 250 g+ for 5–6 h of activity | Low |
| Fat | ~24 g | 50–70 g (hormones, gallbladder) | Low |
| Fibre | ~18 g | 25–30 g | Below target |
| Calcium | ~350 mg | 1,000 mg (bone load from vest) | Low |
| Iron, zinc, vitamin D, omega-3 | little to none | daily | Gaps likely |
| Sodium and fluid | 1 pouch | 3–6 L fluid and electrolytes on walk days | Too little for 6 h |
03Diet plan 2: chicken and protein shake
| Food | Amount | kcal | Protein | Carbs | Fat |
|---|---|---|---|---|---|
| Chicken breast, skinless (weighed raw, then cooked) | 500 g raw | 600 | 112.5 g | 0 g | 13 g |
| Protein powder (whey) | 60 g | 240 | 48 g | 6 g | 3 g |
| Milk for the shake (shake made with water) | 0 ml | 0 | 0 g | 0 g | 0 g |
| Wattie's vege mix | 320 g | 179 | 6 g | 30 g | 1 g |
| Vitasport electrolyte | 1 pouch | 125 | 0 g | 31 g | 0 g |
| Total | 1,144 | 166.5 g | 67 g | ~17 g |
Chicken uses typical raw values (about 120 kcal and 22.5 g protein per 100 g). 500 g raw cooks down to about 350–375 g. The milk is cut to zero and the shake is made with water. Even with no milk, these foods add up to 1,144 kcal, so diet 2 cannot reach 1,000 kcal by cutting milk alone. Getting to 1,000 would mean cutting the chicken to about 380 g raw, which drops protein to about 140 g. Cook chicken until the centre reaches 75 °C.
| Nutrient | Diet 1 | Diet 2 | Needed | Diet 2 status |
|---|---|---|---|---|
| Energy | 976 kcal | 1,144 kcal | ~2,800 kcal | Too low |
| Protein | 72–83 g | ~167 g | ~160 g | Met |
| Carbohydrate | 108 g | 67 g | 250 g+ | Very low |
| Fat | ~24 g | ~17 g | 50–70 g | Very low |
| Fibre | ~18 g | ~11 g | 25–30 g | Low |
| Calcium | ~350 mg | ~300 mg | 1,000 mg | Low |
| Iron, zinc, B vitamins | low | fair (from chicken) | daily | Partly covered |
| Vitamin D, omega-3 | none | none | daily | Missing |
What diet 2 does better
- Protein about 167 g a day, enough to protect much more muscle
- Muscle loss drops from about 10 kg to about 7 kg
- High protein keeps you fuller, so hunger is easier to handle
- Iron, zinc and B vitamins from the chicken
- Strength in the gym holds up better
What is still a problem
- Daily gap of about 2,750 kcal is close to 3 times a safe deficit
- Only 67 g of carbs for 5–6 h of activity: expect fatigue and dizziness on long walks
- Fat about 17 g: very little, so gallstone risk is high at this rate of loss
- Calcium about 300 mg with no milk, a concern for bones under a 20 kg vest
- Fibre about 11 g: constipation is likely with this much protein
- Very repetitive, which makes it hard to stick to for 4 months
- Very high protein needs plenty of water; check kidney function with your GP
To make diet 2 safer, keep the chicken and shake, then add 1–2 tablespoons of olive oil, a piece of fruit or a cup of cooked rice or potatoes around each long walk, and bring back the 50 g of oats. That adds about 600–800 kcal, fixes most of the carbs, fat and fibre, and still loses weight steadily.
04Projected weight over time
The safer line keeps food fixed, so it slows down a lot as you get lighter. Cutting about 150 kcal from your intake for every 5 kg you lose keeps it near 1 kg a week and brings the goal down to about 240 days (around 8 months, early June 2027).
05Before and after
~32% body fat
~10 kg muscle lost
~7 kg muscle lost
~5 kg muscle lost
Assumes ~32% body fat at the start, typical for a 100 kg adult man. A body-scan (DEXA) or a gym body-composition test would give your real starting point.
| Measure | Before | After diet 1 | After diet 2 | After safer pace |
|---|---|---|---|---|
| Weight | 100 kg | 70 kg | 70 kg | 70 kg |
| Fat mass | ~32 kg | ~12 kg | ~9 kg | ~7 kg |
| Muscle and lean mass | ~68 kg | ~58 kg (−10) | ~61 kg (−7) | ~63 kg (−5) |
| Waist | baseline | about 20–30 cm smaller | about 20–30 cm smaller | about 20–30 cm smaller |
| Clothing size | baseline | 2–4 sizes down | 2–4 sizes down | 2–4 sizes down |
| Strength | baseline | likely lower | slightly lower | kept or higher |
| Resting burn (TDEE) | 2,000 kcal | ~1,400 kcal, slowed further by adaptation | ~1,400 kcal, some slowing | ~1,400–1,500 kcal |
| Load on knees per step | baseline | ~120 kg less | ~120 kg less | ~120 kg less |
| Blood pressure (if high) | baseline | often 10–20 mmHg lower | often 10–20 mmHg lower | often 10–20 mmHg lower |
| Chance of regaining it | – | High | High | Lower |
Your BMI at 100 kg and 70 kg
| Your height | BMI at 100 kg | BMI at 70 kg | At 70 kg you'd be |
|---|---|---|---|
| 170 cm | 34.6 | 24.2 | Healthy range |
| 175 cm | 32.7 | 22.9 | Healthy range |
| 180 cm | 30.9 | 21.6 | Healthy range |
| 185 cm | 29.2 | 20.5 | Healthy, lower end |
| 190 cm | 27.7 | 19.4 | Near underweight |
If you're 185 cm or taller, 70 kg would leave you very lean. A goal of 75–80 kg may suit you better and is easier to hold.
06Effects you may notice
Small effects: good
- Scale drops 3–5 kg in week 1 (mostly water and stored carbs)
- Less bloating, clothes feel looser within 2–3 weeks
- Better blood sugar control after meals
- Rowing and walking fitness improve quickly
- Less snoring and easier breathing at night
- Easier to climb stairs and get up from a chair
Small effects: bad
- Constant hunger, cravings, thinking about food
- Tiredness, low energy in the gym, weaker lifts
- Dizziness when standing up quickly
- Headaches, irritability, poor focus
- Feeling cold, poor sleep
- Muscle cramps, sore feet, blisters, shin pain from the vest
- Constipation or, with more fibre, wind
Large effects: good
- Much lower risk of type 2 diabetes
- Lower blood pressure, triglycerides and LDL cholesterol
- Less fat in the liver
- Sleep apnoea often improves or goes away
- Far less wear on knees, hips and lower back
- Better heart and lung fitness
- More confidence, mobility and energy (at a safer pace)
Large effects: risks of this plan
- Muscle loss: roughly a third of the weight lost could be lean tissue
- Gallstones: losing over 1.5 kg a week on very little fat raises the risk sharply
- Bone stress injuries in feet and shins: 30 h a week under 20 kg on little calcium and energy
- Electrolyte imbalance that can disturb heart rhythm
- Hormone drop: low testosterone and libido in men, missed periods in women
- Hair shedding 2–4 months in
- Slowed metabolism and a high chance of regaining weight afterwards
- Low mood, and urges to binge
07What to expect, stage by stage
Fast drop on the scale
3–5 kg gone, mostly water. Hunger, headaches and tiredness are strongest now. Watch for dizziness during the long walks.
Steady loss, rising fatigue
About 2 kg a week. Clothes loosen and blood pressure may start to fall. Gym strength often dips. Foot and shin soreness from the vest is common.
Visible change, highest risk
Big change in face, waist and body shape. This is when gallstone symptoms, stress injuries, hair shedding and hormone changes usually show up. Loss slows as your body gets lighter and adapts.
Goal reached
Much lighter and fitter, but with less muscle and a slower metabolism. Eating normally again brings fast regain unless you raise food slowly over 4–8 weeks and keep training.
08Risk flags
| Risk | Level | Warning signs |
|---|---|---|
| Muscle loss | High | Lifts getting weaker, looking soft or "flat" despite losing weight |
| Gallstones | High | Pain under the right ribs after eating, nausea, yellow skin or eyes |
| Hormone disruption | High | Low libido, missed periods, feeling flat or low |
| Weight regain | High | Strong hunger, binge urges, rapid gain after stopping |
| Fainting or low blood sugar | Medium–high | Shaky, sweaty, light-headed, blurred vision during walks |
| Bone stress injury | Medium–high | Pain in one spot on the foot or shin that gets worse with each walk |
| Electrolyte imbalance | Medium | Cramps, palpitations, confusion, unusual weakness |
| Hair shedding, loose skin | Medium | More hair in the brush around months 2–4 |
Stop and get medical help if you have
- Chest pain, a racing or irregular heartbeat, or fainting
- Severe pain in the upper right belly, or yellow skin or eyes
- Confusion, or severe weakness or cramping
- Bone pain that stops you walking normally
09Recommendations
- See your GP before you start. Ask for blood tests (full blood count, iron, electrolytes, kidney, liver, cholesterol, HbA1c), a blood pressure check and an ECG. Ask them to recheck you every 4–6 weeks.
- Eat more, or train less. With this much exercise, around 2,500–2,800 kcal at the start keeps loss near 1 kg a week. If you'd rather eat less, cut the training so the gap stays under about 1,000 kcal a day.
- Raise protein to about 160 g a day. Diet 2 already does this. Eggs, chicken, fish, Greek yoghurt or a second whey shake all help protect your muscle.
- Add healthy fat, 50–70 g a day. Olive oil, nuts, avocado or oily fish protect your gallbladder and hormones.
- Cover the gaps: calcium-rich dairy, leafy greens, and fruit. Ask your GP about vitamin D, iron and a multivitamin.
- Fuel the long walks: drink 0.5–1 L of fluid an hour with electrolytes, and eat carbs during walks over 2 hours.
- Build up the vest gradually. Start with 5–10 kg and shorter walks, then add weight and time over 4–6 weeks. Take one full rest day a week.
- Track more than the scale: waist measurement, gym strength, sleep, mood and energy.
10Method and sources
Energy burned uses MET values from the Compendium of Physical Activities (Ainsworth et al., 2011): rowing 7.0, weights 5.0 (leg day 6.0), abs 3.8, walking 3.5 with the vest added to body weight. Your TDEE is scaled to your weight each day. 7,700 kcal is counted as about 1 kg lost.
Muscle loss estimates draw on the limit to how fast fat stores can release energy, about 69 kcal per kg of fat per day (Alpert, 2005, Journal of Theoretical Biology). Knee load uses about 4 kg less force per step for each kg lost (Messier et al., 2005, Arthritis & Rheumatism). Blood pressure uses about 1 mmHg per kg lost (Neter et al., 2003, Hypertension).
All figures are estimates for one person following the plan exactly. Real results vary with genetics, sex, age, height, sleep, stress and how closely the plan is followed.