Most people with obesity achieve good results with calorie-restricted diets, yet a small group fails to lose enough weight, even though they follow the dietary guidelines very strictly. These people are called ‘diet-resistant’. The good news is that the right combination of strength and endurance training can change that.
At the University of Ottawa in Canada, researchers studied the effects of physical activity in diet-resistant patients with a BMI above 30 who had barely lost any weight after six weeks on a 900 kcal per day meal-replacement diet.
The researchers compared 20 diet-resistant women with 20 women who lost weight very well on a calorie-restricted diet. They were matched by age, weight and BMI. Everyone’s body composition was measured and all women took part in the same training programme. Over six weeks, all women completed a total of 18 exercise sessions, three times a week with a rest day in between. Each session consisted of 30 minutes of walking on a treadmill, followed by a series of strength exercises. All participants were asked to keep to their normal lifestyle and to record their daily physical activities, in addition to the data provided by their activity tracker. At the same time, their muscle fibre types, the energy-producing function of their cells and other data were analysed.
The study showed that women who lose weight quickly on a low-calorie diet have many advantages for losing weight thanks to the volume and composition of their muscle tissue and their metabolism. However, these women are more likely to develop obesity or metabolic syndrome.
In contrast, diet-resistant women who follow a training programme see a strong improvement in their body composition, muscles and metabolism, which is not the case in the other group. These insights make a more personalised approach to obesity possible for people who previously lost little or no weight through diet. For this group in particular, physical activity is essential for losing weight, and a training programme can really help them slim down.