Background The WHO states that a maximum of 10% of the daily total caloric intake should correspond to the consumption of free sugars. It has been described in a theoretical way that an excessive intake of free sugars may originate, on the one hand, a pancreatic affectation, and on the other hand, an impairment of the connective tissue. Therefore, in this labour is posed the possibility of the affectation of the thoracolumbar fascia (TLF) due to its metameric relationship with the pancreas due to an excessive consumption of free sugars.

Methods An experimental, randomised, prospective and single-blind analytical research is proposed. 4 women were divided into 2 groups, control and experimental ones, by a simple randomization process. Control group subjects had to follow their usual diet while experimental group subjects carried out a low-free sugars diet. Two sonographic measurements were performed using the Toshiba Xario100 ultrasound with a 70 mm linear ultrasound probe, one pre-intervention and another post-intervention, 4 weeks after the beginning of the diets. A blinded external examiner measured the thickness with mode B sonography and the elasticity with an elastography in the L2-L3 interspinous space, and the distances’ difference between L2 and L3 spinous process in anatomical position and in maximum spine flexion position with mode B sonography.

Results An intra-examiner statistical analysis was carried out by implementing the t-Student test for related samples in order to study the pre-post differences in dependent variables. No statistically significant changes (p<0,05) were found in the opening of the L2-L3 interspinous space (t −0,714; p=0,53), neither in the elasticity (t −0,23; p=0,83) or in any of the studied thickness dependent variables: ‘L2 bipe’ (t −0,94; p=0,42), ‘Media bipe’ (t 0,12; p=0,92), ‘L3 bipe’ (t −1,46; p=0,24), ‘L2 flexion’ (t −2,10; p=0,13), ‘Media flexion’ (t −0,72; p=0,52) and ‘L3 flexion’ (t −1,25; p=0,30).

Conclusions The results suggest that a low-free sugars diet produces no improvements in the L2-L3 interspinous opening, neither in the thickness or the elasticity of the TLF in the L2-L3 interspinous space. To confirm the results, prospective randomised clinical trials with equal representation of both genders, larger samples and longer follow-ups are needed. Likewise, we recommend future studies using expert examiners that compare their measurements with a gold standard test.