How to start losing weight: the first 4 weeks without a crash diet

Most people who come to me have started a diet before. More than once. Usually on a Monday, and usually with everything at once: counting calories, training four times a week, no more sugar, no more wine. By Thursday the plan is dead, and what stays in the head is "it did not work again". Here are the first four weeks laid out so you can live them in a normal week with work and kids.

Short answer: Start with one change per week. In week 1 only log what you eat and eat as usual. In week 2 set a deficit of roughly 15 to 20 percent below your energy use. In week 3 build your meals around protein. In week 4 add two strength sessions a week and walking.

One change per week. Nothing more.

If you have a history of an eating disorder, are pregnant or breastfeeding, or take medication that affects appetite or weight, talk to your doctor before you start a deficit or daily weighing.

Week 1: change nothing yet, just look

Your only task in the first week is to find out where you are. Write down what you eat and drink, in any app or a notebook, and eat exactly as usual. If you start logging and trying to be good at the same time, all you learn is what your best week of the year looks like.

Why you should not skip this step: in a US study, 10 people who said they could not lose weight even on under 1,200 kcal (calories) a day were measured. Their energy expenditure was normal. But they underreported their actual food intake by 47 percent on average and overreported their activity by 51 percent (Lichtman, 1992, NEJM, PMID 1454084). Estimating food by eye is hard, even for people who try to be honest.

Programs that include food logging tend to work. A systematic review of 59 studies in adults with overweight and obesity found that most programs with food logging led to statistically significant weight loss against control groups, both with detailed logging and with the simpler kind (Raber, 2021, PMID 34412727). The review could not say how much of the effect comes from the logging itself.

By the end of the week you have a number you can work with. That is the whole goal.

Week 2: set a deficit that survives a Friday night

Now the calories go down. A reasonable start is roughly 15 to 20 percent below your estimated energy use. For most of my clients that means a pace somewhere between 0.3 and 0.7 kg a week, and above all it means you can live with it.

A kilo of body fat is about 7,700 kcal. A deficit of 500 kcal per day gives you about half a kilo a week (7 x 500 = 3,500 kcal = about 0.45 kg). No app or formula hits it exactly the first time. You fine-tune the numbers as you go, based on the scale. The method and the calculation are in calorie deficit: how much to eat, and the calculator gives you a starting estimate.

What to avoid: a jump to 1,000 to 1,200 kcal. For most of my clients the hunger gets so strong that the diet breaks within weeks, and more muscle goes with it. A slower pace that you keep for half a year takes you further than a hard ten-day diet.

Week 3: build your plate around protein

With fewer calories comes hunger. That is exactly why protein comes in week 3, not a year later.

In a study of 46 women with overweight and obesity, everybody followed a diet with a 750 kcal daily deficit for 12 weeks. One group ate 30 percent of energy from protein, the other group 18 percent. Weight loss was similar, but the higher-protein group lost less lean mass (1.5 kg against 2.8 kg) and its fullness dropped less (Leidy, 2007, PMID 17299116).

In practice: aim for roughly 1.6 to 2.2 g of protein per kg of body weight a day, with protein in every main meal. If you have a lot to lose, calculate it from your goal weight instead of your current weight. Meat, fish, eggs, quark (a fresh cheese, similar to strained Greek yogurt), skyr, beans and lentils, and whey protein when you can't fit it in. Details are in how much protein, the protein tool ranks foods by protein per 100 kcal, and the full plate is in what to eat to lose fat.

Don't worry about the rest of the menu yet. Add vegetables to lunch and dinner and otherwise eat what you ate before, just in smaller amounts.

Week 4: add strength and walking

Only now does movement come in, and not for the calories it burns. Strength training in a deficit protects the muscle you would otherwise lose together with fat.

A meta-analysis of 65 studies with 2,537 adults with overweight and obesity reports for strength programs an average fat loss of 1.6 kg and a gain of 0.8 kg in lean mass (everything that is not fat, mostly muscle and water). Programs that combined lifting with calorie restriction showed a drop in lean mass (Lopez, 2022, PMID 35977113). In a deficit, don't expect to build much. The goal of lifting is to keep as much muscle as you can while the fat comes off. It also affects how you look at the end, because the same weight lost can look quite different.

To start, two strength sessions a week of 40 minutes are enough, with your body weight and one dumbbell if you like. Add walking. Steps are one of the cheapest ways to raise daily energy use without having to grind anything out, and I wrote about them in how many steps a day.

When the scale does not move for a week

It happens to nearly every client I coach, and it is normal. The scale also shows water, gut contents and, for women, the phase of the cycle, so two kilos up and down in one week say nothing about fat. More on this in why your weight fluctuates.

What to do: weigh yourself every morning after the toilet and compare weekly averages, not single mornings. If the average doesn't move for two weeks in a row while you log honestly, cut about 10 percent of calories or add 2,000 steps a day. One of the two, not both at once.

What to skip: adding more bans. Throwing out bread and cutting fruit won't help when the total intake doesn't fit. Why fast starts rarely last is in yo-yo dieting.

Frequently asked questions

Do I have to count calories forever?

No. A few weeks of logging teach you to estimate portions. Then most of my clients move to a looser mode and come back to counting only when progress stalls.

How many kilos a month is reasonable?

For most of my clients a pace of about 0.5 percent of body weight per week fits. That is roughly 1.5 to 3 kg a month, depending on how much you weigh. The first week of the deficit is often clearly higher, because retained water leaves.

Can I start without exercise?

Yes, you lose weight from a deficit in food. Without strength training you lose more muscle, and with it some strength and shape. If there is no room for training now, start with food and walking and add strength when the first part has settled.

Sources, so you can check:

1) Underreported intake: Lichtman SW, et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. N Engl J Med. 1992;327(27):1893-1898. DOI: 10.1056/NEJM199212313272701 | PMID: 1454084

2) Food logging: Raber M, et al. A systematic review of the use of dietary self-monitoring in behavioural weight loss interventions. Public Health Nutr. 2021;24(17):5885-5913. DOI: 10.1017/S136898002100358X | PMID: 34412727

3) Protein and muscle in a deficit: Leidy HJ, et al. Higher protein intake preserves lean mass and satiety with weight loss in pre-obese and obese women. Obesity (Silver Spring). 2007;15(2):421-429. DOI: 10.1038/oby.2007.531 | PMID: 17299116

4) Strength training and body composition: Lopez P, et al. Moderators of Resistance Training Effects in Overweight and Obese Adults: A Systematic Review and Meta-analysis. Med Sci Sports Exerc. 2022;54(11):1804-1816. DOI: 10.1249/MSS.0000000000002984 | PMID: 35977113

Martin Barna

Online nutrition and fitness coach. Since 2013 I have coached 600+ clients. I work with what the research shows and what my clients can keep doing.

Apply for coaching

This article is for information only. It is not medical advice. If you have a health condition, talk to your doctor.