Intermittent fasting can lead to greater short-term weight loss than traditional low-calorie diets, Malaga scientists have found.
A new study found that modified alternate-day fasting and late time-restricted eating deliver better results over three months than the standard calorie-cutting plans widely used to treat obesity.
The investigation was led by Francisco J. Tinahones, scientific director of the Malaga Biomedical Research Institute (Ibima).
Published in BMC Medicine, the research compared several nutritional strategies: a ketogenic diet, modified alternate-day fasting, early time-restricted eating and a classic low-calorie Mediterranean-style diet.
All plans controlled calorie intake, but the first three produced significantly greater reductions in weight and body fat.
The findings come amid reports that obesity could affect nearly half of the world’s population between 2030 and 2035.
The condition raises the risk of cardiovascular disease, diabetes and a long list of chronic illnesses.
To assess each diet, researchers ran a three-month randomised clinical trial involving 160 adults with obesity. According to Ibima, the design and close monitoring of participants provide robust evidence to guide more personalised nutritional treatments.
Results showed the ketogenic diet produced the greatest loss – an average of 11.9kg in three months, around 3.8kg more than those following the traditional low-calorie plan.
While every group lost weight, the classic diet group shed an average of 8.4kg.
Fasting-based approaches stood out for reducing body fat, particularly the modified alternate-day fasting method.
No serious adverse events were reported, strengthening the case for the short-term safety of these strategies.
Tinahones said the findings ‘give us new tools in the fight against obesity’.
Traditional low-calorie diets are still valuable, he noted, but the data support ketogenic and intermittent-fasting approaches for achieving faster results in people with obesity.
‘This encourages us to widen the range of nutritional strategies and adapt them to each patient’s needs and preferences,’ he added.
Alternate-day fasting is a form of intermittent fasting where you alternate between ‘fast days’ and ‘normal eating days.’
There are two common versions, including strict ADF, which is when you eat nothing (or almost nothing) on fast days and eat normally the next day.
There is also modified ADF, the version used in most clinical studies (including the Malaga one). On fast days, you still eat a small controlled amount – usually around 500–600 calories. The following day, you return to normal eating, without overeating to ‘make up’ for the fast.
Time-restricted eating means you only eat within a fixed daily eating window. ‘Early’ simply means that the window is placed earlier in the day, usually finishing mid-afternoon.
In most studies, you eat all your meals within six to eight hours, and eating typically ends by 4pm. No calories are consumed the rest of the day and night.
