Why am I not losing weight? Common mistakes and how to fix them

Why am I not losing weight if I am eating less?

The most common cause is eating a little more than you think, without meaning to. Oil poured by eye, nibbling while cooking, drinks, meals out and weekends all add up. Underestimating what you eat is very common, and it is enough to make a small deficit disappear.

In the first week, weight usually drops quickly, mostly because of water and glycogen (the sugar store in muscle and liver). After that phase, a realistic pace is around half a kilo a week. We explain this in more detail in the weight loss diet guide.

If the scale stops moving for two or three weeks, you have not failed. Often it is fluid retention because of your period, stress or starting to train. Also, as you lose weight you burn slightly less, because your body has less weight to move, and the margin of the plan narrows. If it goes on for more than a month while you follow the plan, review the mistakes that follow.

Does cutting calories too much slow weight loss?

Cutting a lot makes you lose weight at first, but it is very hard to maintain. Having just a piece of fruit or lettuce with turkey for dinner leaves a hunger that ends in snacking or an out-of-control weekend. Those excesses wipe out the deficit of the whole week.

When you suddenly eat much less, the body burns slightly less at rest and you move less without realising. This is metabolic adaptation, real but smaller than is often believed. Staying hungry continuously also makes you lose muscle mass, and with it part of your daily energy expenditure.

The British obesity guideline reserves plans of 800 to 1,200 kcal for specialist units with long-term follow-up [2]. Below 800 kcal, these are very-low-calorie diets, which require medical supervision [2][3]. At Alimmenta we do not recommend diets of less than 1,200 kcal a day. Going below that amount requires medical supervision and can cause nutrient deficiencies. On your own, they are also hard to sustain and encourage weight regain.

What mistakes do we see in consultations?

Three mistakes come up every week in consultations, and all three start from good intentions.

Cutting out carbohydrates all at once

Giving up bread, rice, pasta, potatoes and pulses makes the number on the scale drop within a few days. What is lost is mostly the water that goes with glycogen. In the medium term it is hard to keep up. Sweet cravings, afternoon snacking and the feeling of always restricting yourself appear.

The plate method works better: half a plate of vegetables, a quarter of protein and a quarter of carbohydrates, preferably wholegrain. If you need to cut calories, the Spanish Agency for Food Safety and Nutrition (AESAN) advises not going above four servings of cereals a day [1].

Swapping meals for juices or smoothies

When fruit is squeezed or blended, almost all its fibre is lost, and one glass holds several pieces. You take in a lot of sugar within a few seconds and without chewing, so hunger returns soon. Nor do you need to “cleanse” your body with drinks, because the liver and kidneys already take care of that. Whole fruit keeps its fibre and fills you up more.

Eating healthily without looking at quantity

Eating healthily helps, but it does not guarantee weight loss. Olive oil, nuts, avocado or dark chocolate are good choices with a lot of calories in a small volume. Dressing by eye or snacking on handfuls of nuts through the day adds hundreds of calories without you noticing.

With fruit it is the other way round, because it provides volume and few calories at any time of day. Having it for dessert or at night does not make you gain more. For light, complete dinners, see our dinner ideas for weight loss.

Does exercising without changing your eating help you lose weight?

Many people think that because they go running or to the gym, they can be careless about food. Physical activity looks after the heart, sleep and muscle, but it burns less than we tend to think. What you burn in a session is replaced by a couple of biscuits and a soft drink.

The World Health Organization (WHO) recommends 150 to 300 minutes a week of moderate aerobic activity [4]. For what you lose to be fat and not muscle, it is worth adding strength training two or three days a week [3].

If you live with significant excess weight, also see the guide on obesity. Energy balance still depends mostly on what you put on your plate.

If you sleep little or live with stress

Sleeping little disrupts appetite. Lack of sleep is associated with less leptin, the hormone that signals fullness, and more ghrelin, the one that triggers hunger. The next day you crave foods rich in fat and sugar more. For most adults, adequate rest is between seven and nine hours [5].

Sustained stress also weighs on you. It tires you, takes away time to organise meals and pushes you to seek food as quick relief, which we call emotional hunger. Looking after your sleep and finding breaks counts for weight loss as much as the menu does.

What medical problems or medicines can stop you losing weight?

If you have been following a tight plan well for weeks and your weight does not change, it is worth ruling out medical factors. Untreated hypothyroidism can reduce energy expenditure and encourage fluid retention. Once treated, it stops being the brake.

Polycystic ovary syndrome (PCOS) is often associated with insulin resistance, meaning this hormone works less well, and with a greater tendency to gain weight [6]. Prediabetes and metabolic syndrome also deserve medical review.

Some common medicines can promote weight gain. This is the case with corticosteroids, certain antidepressants and antipsychotics, or some diabetes medicines [3]. Do not stop or change your medication on your own. Talk to your doctor before blaming the plateau on the plan.

When the problem is your relationship with food

If eating has become a constant source of distress, guilt or obsessive thoughts, another plan will not solve it. It is common to restrict heavily during the week, lose control or binge at the weekend and then punish yourself with fasting or gruelling exercise. This is the cycle fuelled by plans that promise to lose a lot of weight in a short time.

If you feel that food controls your emotions, that you eat in secret or that you cannot stop once you start, the first step is psychology specialised in eating behaviour. It is best to seek that help before following another plan. From there, a calm relationship with food and with your body is built, without guilt or punishment.