How to Lose Weight Safely and Keep It Off

In brief: to lose weight safely, eat a little less than your body uses, move more, and go slowly. The NHS suggests losing 0.5 to 1 kg (1 to 2 lb) a week. The NIH suggests a first goal of 5% of your body weight over 6 months. Pair a modest calorie deficit with balanced meals, at least 150 minutes of activity a week, good sleep and support, then weigh yourself regularly and adjust.

How to Lose Weight Safely: The Targets at a Glance

Safe weight loss is slow, steady and something you can keep doing. Public health bodies agree on a handful of targets, summarized below.

What to aim for	Target	Source
Weekly rate of loss	0.5–1 kg (1–2 lb) a week	NHS
First goal	5% of body weight over 6 months	NIDDK (NIH)
Health payoff	Losing 5–10% of body weight can improve health	NHS
Aerobic activity	150+ minutes of moderate activity weekly	US and UK guidelines
Strength work	Muscle-strengthening 2+ days weekly	US and UK guidelines
Monitoring	Track food and activity daily, weight weekly	NIDDK (NIH)

None of these targets asks for a dramatic change. That's the point. A plan you can follow for a year beats a strict plan you abandon in three weeks.

How Fast Can You Lose Weight Safely?

For most adults, 0.5 to 1 kg (1 to 2 lb) a week is the safe pace the NHS recommends. Going faster usually means a very large calorie deficit, and that is much harder to keep up.

The NIH frames the first target more gently still. It suggests that a reasonable first target is to lose 5% of your starting weight across roughly six months. For someone who weighs 200 lb (91 kg), that's 10 lb (4.5 kg). Small as it sounds, the NHS notes that losing 5 to 10% can already improve your health.

Very low calorie diets sit outside this range. The NHS describes them as diets under 800 or 1,200 calories a day. It says they are not safe or suitable for everyone, and that they are normally used only with a dietitian's support when weight is affecting another health condition. Don't try one on your own.

Our calorie goal calculator flags any pace faster than 1% of your body weight a week, and any target that falls very low.

Step 1: Know Your Starting Point

Before you change anything, find out where you are. Three numbers help:

• Body mass index (BMI): a quick screen of weight for height. For most adults, the NHS treats 25 to 29.9 as overweight and 30 or more as obese, with lower cut-offs for people of some ethnic backgrounds.
• Waist size: the NHS suggests keeping your waist under half your height. This picks up fat around the middle that BMI can miss.
• Maintenance calories: the energy you use in a day, which is the number your deficit is taken from.

Write these down, along with your current weight. They are your baseline for every later decision.

Step 2: Create a Modest Calorie Deficit

You lose weight when you take in fewer calories than your body uses, so the stored energy makes up the difference. As a rough guide, the NHS puts average daily use at about 2,000 calories for women and 2,500 for men, but your own figure depends on your size, age and activity.

Aim for a deficit you barely notice, not one that leaves you hungry all day. Our guide to the calorie deficit you need to lose weight explains how to size it. In short, a deficit of around 250 to 550 calories a day lines up with the NHS weekly target for most people.

Expect the rate to slow. Research from the NIH shows that the calories stored per kilogram of weight lost vary with how much body fat you start with. The classic "3,500 calories per pound" rule roughly fits people with plenty of fat to lose, but overstates the deficit leaner people need. Recalculate your target every few kilograms.

Step 3: Improve What You Eat, Not Just How Much

The quality of your food makes a smaller deficit easier to live with. The NIH points to the eating pattern in the Dietary Guidelines for Americans:

• vegetables of every kind, and fruit, preferably whole rather than juiced
• whole grains such as oats, brown rice and whole-wheat bread
• low-fat or fat-free dairy, or fortified soy alternatives
• protein from a mix of lean meat, poultry, eggs, seafood, beans, lentils, nuts and seeds
• oils such as olive oil instead of solid fats

The same guidelines suggest keeping added sugars and saturated fat each below 10% of daily calories, and sodium under 2,300 mg a day. For meal-by-meal ideas, see healthy eating for weight loss.

Step 4: Move More

Activity burns extra calories and, just as importantly, helps you keep lost weight off. The UK and US guidelines both set a baseline of 150 minutes or more of moderate activity weekly, such as brisk walking or cycling, plus muscle-strengthening work for every major muscle group, two or more days a week.

For weight loss, more is often needed. The NHS suggests 45 to 60 minutes of activity a day, which you can split into shorter sessions. The US guidelines note that people losing more than 5% of their body weight may need more than 300 minutes a week. They also found that combining fewer calories with more activity tends to work better than either one alone.

If you're starting from very little, begin with 10-minute walks and build up. Every bit counts toward the weekly total.

Step 5: Sleep, Setbacks and Support

Weight loss is not only about food and exercise. The NHS points out that short sleep can make high-calorie food more tempting and leave you too tired to cook or be active. A regular bedtime is a genuine part of the plan.

Plan for setbacks rather than fearing them. A big meal at a party doesn't undo weeks of progress. The NIH advice is simply to return to your usual plan at the next meal.

Support makes a measurable difference too. Tell someone you trust about your goal, and consider a structured program if you'd like more help. Our guide on how to choose a weight loss program covers what good ones include.

How to Lose Weight for Women and for Men

The method is the same for everyone: a modest deficit, better food, more movement. What differs is the size of the numbers.

Women generally need fewer calories than men, so the same deficit is a bigger share of their daily intake. Men often lose weight a little faster on paper. Research by the NIH's Kevin Hall suggests one reason: women usually carry more body fat than men of the same weight, and fat stores more energy per kilogram, so each kilogram takes a larger deficit to lose. Neither pattern means one sex is "better" at losing weight. Compare your progress only with your own starting point.

A Worked Example: Setting a First Goal

Take Maria, 45, who weighs 92 kg (203 lb).

• First goal (NIH): 5% of 92 kg is 4.6 kg (about 10 lb) over 6 months. That's an average of about 0.18 kg (0.4 lb) a week.
• Bigger goal (NHS): losing 10% would be 9.2 kg (about 20 lb), the top of the range linked to health gains.
• Upper limit: 1% of her weight is 0.92 kg (about 2 lb) a week, which is also the top of the NHS range. Our calculator warns about anything quicker.
• Calories: at roughly 7,700 calories per kilogram, losing 0.5 kg (1 lb) a week needs a deficit of about 550 calories a day. A slower 0.25 kg (0.5 lb) a week needs about 275.

Maria chooses 0.25 to 0.5 kg a week, enters her details in a calculator to find her maintenance calories, and subtracts 275 to 550. She weighs herself once a week and reviews the target after a month.

Limits and When to Get Advice

These targets are for healthy adults. They aren't suitable during pregnancy or breastfeeding, for anyone under 18, or for people with an eating disorder now or in the past.

Speak to a doctor before you start if you have a long-term condition such as diabetes, heart disease or high blood pressure, or take regular medicines. The NHS also suggests seeing a GP if your BMI is high and you want help, your waist is more than half your height, or you suspect an eating disorder, binge eating included. Medical treatments exist when lifestyle changes aren't enough; read about weight loss medication.

Frequently Asked Questions

How much weight can you lose safely in a month?

At the NHS rate of 0.5 to 1 kg (1 to 2 lb) a week, that's roughly 2 to 4 kg (4 to 8 lb) a month. Your weight also moves up and down from day to day, so judge progress on the trend across several weeks rather than any single weigh-in.

What is the safest way to lose weight fast?

There isn't a safe shortcut for most people. Very low calorie diets can cause rapid loss, but the NHS says they are only for some people and should be followed with a dietitian's support. For everyone else, the safest fast pace is the top of the NHS range: about 1 kg (2 lb) a week.

Do I need to exercise to lose weight?

You can lose weight through diet alone, because the calorie deficit does most of the work. But the US guidelines found that combining fewer calories with more activity tends to work best, and regular activity is one of the strongest habits for keeping weight off afterward. It also brings health benefits that don't depend on the scale.

Is losing weight different for women over 50?

The principles are the same. Age is one of the inputs in calorie formulas, so your maintenance number will usually be lower than it was at 30. Strength exercises are worth keeping in the plan, because the US guidelines note they help hold on to lean mass while you lose weight. If you have a health condition or take regular medicines, check with your doctor before cutting calories.

To get a daily calorie target and a realistic finish date, use the calorie goal calculator.