How fast should you lose weight?
Losing weight fast feels productive, but past a certain point you lose muscle, strength and your motivation. Here's the rate the research supports.
When you start a diet, the temptation is to go hard. Cut everything, eat 1,000 calories a day, drop five kilos in a fortnight. It works on the scale for a while. Then you’re hungry, flat in the gym, and back where you started by winter.
There’s a better rate.
The sweet spot: 0.5 to 1 percent a week
A review of evidence for lean people losing weight while lifting recommended a rate of about 0.5 to 1 percent of body weight per week. That’s fast enough to see clear progress each month, and slow enough to protect your muscle.
| Body weight | 0.5% a week | 1% a week |
|---|---|---|
| 60 kg | 0.3 kg | 0.6 kg |
| 80 kg | 0.4 kg | 0.8 kg |
| 100 kg | 0.5 kg | 1.0 kg |
If you have a lot to lose, the top of that range is reasonable early on. If you’re already lean, stay near the bottom.
Why slower keeps more muscle
A study of elite Norwegian athletes compared two groups who lost the same total amount of weight, one at about 0.7 percent a week and one at about 1.4 percent. The slower group gained lean mass and improved several strength measures. The faster group didn’t gain lean mass.
The mechanism is simple. A large deficit gives your body a stronger reason to use muscle for fuel, and it leaves less energy for training hard enough to keep that muscle.
What 0.5 kg a week looks like in calories
A kilogram of body fat holds roughly 7,700 calories. To lose 0.5 kg a week, you need a deficit of about 3,850 calories a week, or 550 calories a day. For most people that’s the difference between a takeaway dinner and a home cooked one, plus a daily walk.
Keep a floor under it. We don’t suggest going below about 1,500 calories a day for men or 1,200 for women without supervision, and never below your resting burn. If your numbers say you need to, choose a slower rate. Logpulse caps weekly loss at 1 percent of body weight for this reason.
Expect it to slow down
As you get lighter, you burn less. Your body also tends to move a bit less when you diet, often without you noticing. So the same intake produces slower loss over time. That’s normal, and it’s why you review your numbers every couple of weeks instead of setting them once. See how many calories you actually need.
Diet breaks work
In the MATADOR trial, men with obesity either dieted continuously for 16 weeks, or dieted in two week blocks separated by two weeks eating at maintenance. The intermittent group lost more fat overall and kept more of it off six months later.
You don’t need a formal protocol. If you’re worn out after two or three months, a week or two at maintenance is a smart move, not a failure.
How to tell if you’re on track
Watch your weekly average, not daily weigh ins. Daily weight can swing a kilo or more from water and food alone. If your average is moving at roughly the rate you planned over two to three weeks, leave things alone. If it’s stalled for three weeks, cut 100 to 150 calories or add some steps.
The Logpulse Progress tab draws your planned rate as a line and your actual trend beside it, so you can see at a glance whether you’re ahead, on track or drifting.
This is general information drawn from published research, not personal medical or dietary advice. If you have a health condition, are pregnant, or have a history of disordered eating, speak to your GP or an Accredited Practising Dietitian first. For support with eating concerns, the Butterfly Foundation helpline is 1800 33 4673.
Sources
- Helms ER, Aragon AA, Fitschen PJ. Evidence based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition. 2014;11:20.
- Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot Borgen J. Effect of two different weight loss rates on body composition and strength and power related performance in elite athletes. International Journal of Sport Nutrition and Exercise Metabolism. 2011;21(2):97 to 104.
- Byrne NM, Sainsbury A, King NA, Hills AP, Wood RE. Intermittent energy restriction improves weight loss efficiency in obese men: the MATADOR study. International Journal of Obesity. 2018;42(2):129 to 138.