Weight loss in Trento: why strength training matters more than diet alone

Losing weight and losing fat are not the same thing

People starting a weight-loss journey almost always look at the scale, and that is understandable: it is the easiest number to measure. The problem is that the scale adds up everything the body loses and does not tell fat, water and lean tissue, muscle included, apart. When weight goes down, the useful question is therefore not only "how much?" but "what am I losing?". This is where strength training comes in, with a role that differs from that of diet and cardio.

In this article we lay out what the scientific literature indexed on PubMed lets us say today, with its numbers and with its limits. You will not find promises of fast or guaranteed results: no study supports them, and the outcome depends on many individual variables, from nutrition to consistency, from starting point to each person's medical history.

Aerobic, strength or both: what the meta-analyses say

A systematic review and meta-analysis published in 2025 in the Journal of the International Society of Sports Nutrition (Lafontant and colleagues) compared resistance, aerobic and concurrent training (the two combined) in healthy adults, including 36 studies with 1564 participants; 31 of these had enough data for the quantitative part. In programmes lasting at least 10 weeks, aerobic training reduced both body mass (1.82 kg more) and fat mass (1.06 kg more) than resistance training alone, but it was also associated with lower retention of lean mass (0.88 kg less). Concurrent training reduced fat mass by 1.09 kg more than resistance training alone. In studies shorter than 10 weeks no significant differences emerged between modalities, and when workloads were matched the results were similar. The authors conclude that resistance training, when included in a combined programme, neither improved nor impeded fat loss.

A consistent finding comes from a 2023 meta-analysis in Frontiers in Endocrinology (Khalafi and colleagues), which analysed 101 studies covering 5697 postmenopausal women. Compared with control groups, exercise increased muscle mass and fat-free mass and reduced fat mass, body fat percentage, waist circumference and visceral fat. In subgroup analyses, aerobic and combined training showed greater benefits on fat mass, while resistance and combined training showed greater benefits on muscle mass. The authors' conclusion is cautious: combining the two types of training may be a viable strategy to improve body composition. This is, however, a specific population that cannot automatically be extended to everyone.

A third meta-analysis, from 2021 in Biology (Ramos-Campo and colleagues), evaluated circuit-based resistance training: 45 studies were included, with 58 experimental groups (897 participants) and 34 control groups (474 participants). The programmes were associated with an average 1.9% increase in muscle mass and a 4.3% decrease in fat mass, along with a 6.3% improvement in VO2max. The authors also note that low and moderate intensities and short rest between exercises were associated with larger reductions in fat mass. These are average changes across heterogeneous populations and do not describe what any single person will achieve, but they show that weight training set up as a circuit can also engage cardiorespiratory fitness.

Training while eating less: the case of lean mass

The question becomes more concrete with a calorie-restricted diet, because calorie restriction reduces both fat mass and lean mass. A systematic review and meta-analysis published in 2026 in Diabetes, Obesity and Metabolism (Deller and colleagues) pooled 34 randomised trials with 1455 people who were overweight or had obesity, comparing calorie restriction alone with calorie restriction combined with different types of training. Adding exercise was associated with 0.87 kg more fat-free mass than diet alone (95% confidence interval: 0.59 to 1.16 kg), meaning that, on average, nearly half (45.7%) of the fat-free mass loss was prevented. In the network analysis, mixed training gave the largest difference (+1.20 kg), followed by strength training (+0.83 kg); aerobic training (+0.51 kg) fell short of statistical significance. The authors point out, however, that the comparison between modalities showed no significant differences and that only two studies directly measured skeletal muscle mass.

One piece of nutrition data is worth citing, with caution. In a 2016 randomised trial in the American Journal of Clinical Nutrition (Longland and colleagues), 40 young men (20 per group) followed for 4 weeks a diet with an energy deficit of about 40% relative to their requirements, combined with six days a week of resistance training and high-intensity intervals. Those consuming 2.4 g of protein per kg per day gained 1.2 kg of lean mass (versus 0.1 kg with 1.2 g/kg) and lost 4.8 kg of fat mass (versus 3.5 kg). It is, however, a very intense, short protocol in young men: it is not a model to copy, and how much protein to eat should be worked out with a nutrition professional, taking age and health conditions into account. An older systematic review, from 2010 in Nutrition Reviews (Weinheimer and colleagues), covering 52 studies in middle-aged and older adults with overweight or obesity, reports in a non-quantitative way, because the data were insufficient for a meta-analysis, that exercise, mostly aerobic, helps preserve lean mass after weight loss from moderate energy restriction.

The limits of what we know

Before drawing conclusions it helps to look at the boundaries. The research cited covers different populations (healthy adults, postmenopausal women, people with overweight, young men), different durations and very heterogeneous protocols. The average differences in kilograms are small relative to total body weight and do not say who will respond more or less. In the 2026 meta-analysis only two studies measured skeletal muscle mass in the strict sense, while the others used fat-free mass, which also includes water, organs and bone. Longland's work is a small, short study, and Weinheimer's is a non-quantitative review. The numbers should therefore be read as indications of a trend, not as individual predictions.

What this means if you want to lose weight

In practice, the data do not say that strength training makes you lose weight faster: to reduce absolute fat mass, aerobic and combined training showed an advantage over resistance training alone, and adding strength work to aerobic training did not appreciably change fat loss. They do say, however, that when you eat less, including strength training is associated with a smaller loss of lean mass, and therefore a more favourable body composition for the same weight lost. It is a qualitative advantage that the scale alone does not show. This is why, when we set up a weight-loss programme, strength training is not an accessory: it is the part that helps limit muscle loss while the rest of the programme works on fat, in coordination with adequate nutrition.

One last note: everyone starts from a different situation, and a weight-loss programme, especially in the presence of medical conditions, medications, pregnancy or a history of eating disorders, should be discussed with your doctor and a nutrition professional before you begin. This article is for information only and does not replace medical advice.