Obesity: what diet can do and what it cannot

What is obesity and why is it considered a chronic disease?

The World Health Organization describes obesity as a chronic disease in which biological, social and environmental factors interact [3]. The Spanish guideline stresses that it can return and needs long-term follow-up [4]. Obesity has diverse causes and effects; it is not explained by a single behaviour [3].

The body mass index (BMI) relates weight to height and is used to classify obesity in broad population groups. It has limits, because it does not tell fat from muscle or say where fat is stored.

To understand what a number can and cannot tell you, see our guides on underweight, normal weight, overweight and obesity and body composition.

That is why the goal is long-term health. In people at high risk of diabetes, losing between 5 and 10 % of body weight gradually over a year can reduce that risk [1]. Talk with the team about which goal is right for you.

And because obesity tends to return, follow-up continues over time [4].

Why is obesity not a matter of willpower?

One of the biggest obstacles is stigma. It is assumed, with no scientific basis, that a high weight is the result of laziness or lack of self-control. The Spanish obesity guideline refutes this.

The guideline describes obesity as a chronic, multifactorial disease and asks us to avoid the stigma of blaming it on a lack of willpower [4].

When body fat falls, levels of leptin, the hormone that curbs appetite, drop. The guideline links this adaptation to increased hunger [4]. That is why follow-up also needs to take into account each person’s environment and circumstances.

On top of this comes the environment. There are cheap, very high-calorie ultra-processed foods at any hour, sedentary working days and constant stress. Blaming the person only causes suffering and delays them asking for help.

What diet can do and what it cannot

Diet is a central part of treatment, but it does not work alone. Knowing how far it goes avoids frustration.

A suitable diet can help you to:

• Improve your lipid profile, even without losing weight [2].
• Reduce the risk of type 2 diabetes and cardiovascular disease [2].
• Fit each person’s needs and preferences, without turning a single food into a treatment.
• Lose fat gradually without constant hunger, with filling, fibre-rich foods.

What diet alone cannot do:

• Resolve obesity once and for all, because it is chronic and calls for habits that last.
• Replace drug treatment when your doctor prescribes it.
• Address eating to soothe emotions. If you eat to calm anxiety or sadness, you need psychological support.

NICE, the British institute that produces clinical guidelines, advises against excessively restrictive and unbalanced plans. They do not work in the long term and can be harmful [2].

How an eating plan is put together

The NICE guideline proposes an energy deficit, that is, eating less energy than you use [2]. The plan is adapted to your needs and preferences. It does not guarantee that all muscle is kept, and by itself it does not stop weight from coming back.

A plan you can keep up for a year is worth more than one you last three weeks on.

On the plate, the most practical split has three parts. Half, a variety of vegetables. A quarter, protein, such as fish, eggs, poultry, pulses or tofu. And another quarter, quality carbohydrates, such as brown rice, potato, pasta or wholemeal bread.

There is one safety limit on calories. At Alimmenta we do not publish or suggest diets of less than 1,200 kcal a day. If you plan a long-term diet, ask for supervision from a nutritionist or your doctor [2].

If you are offered shortcuts, in our guide to plans that promise effortless weight loss we explain why they do not hold up and what risks they carry.

Why does strength exercise matter so much in obesity?

The Spanish guideline includes strength exercise within care adapted to the person [4]. Weights, resistance bands or your own body weight all work. What counts is that the muscle works against resistance.

To start at home, sit-to-stand squats to a chair, wall push-ups and the glute bridge are enough, on two non-consecutive days.

For the adult population, the WHO recommends between 150 and 300 minutes a week of moderate aerobic activity and strength exercises on at least two days a week [5]. Brisk walking, climbing stairs and moving about during the day add to strength work.

What mistakes do we see in consultation?

These mistakes come up again and again in consultation. None of them has to do with willpower.

• Starting with the hardest part. A very low-calorie plan on Monday that by Thursday you can no longer keep up. It is worth reviewing which changes you can maintain.
• Leaving strength work until you have lost weight. Ask from the start which exercise is right for you.
• Arriving at dinner enormously hungry. Note whether eating very little during the day leaves you hungrier at night.
• Measuring progress only with the scale. Agree with the team how to follow changes in weight and waist. Blood tests, sleep or getting less tired climbing stairs also count.

Obesity: treatment with and without drugs

In some cases, the treatment of obesity includes drugs [4].

These are prescription medicines. Your doctor prescribes, monitors and adjusts them, and they should not be obtained on your own. Nor do they replace changing habits.

During treatment, nutritional support lets you review what you can eat and how your strength and weight are changing. Diet and strength work are reviewed during treatment; any change of medication is decided with whoever prescribes it. We work on this in our nutritional support during GLP-1 treatment.

If you want to compare the options, see our guide to Ozempic, Wegovy and Mounjaro. Choosing a treatment requires an individual medical assessment.