Effect of 5:2 Regimens: Energy-Restricted Diet or Low-Volume High-Intensity Interval Training Combined With Resistance Exercise on Glycemic Control and Cardiometabolic Health in Adults With Overweight/Obesity and Type 2 Diabetes: A Three-Arm Randomized Controlled Trial
Question
Do 5:2 regimens using either 2 days per week energy-restricted diet or 2 days per week low-volume HIIT combined with resistance training improve glycemic control and cardiometabolic health compared with routine lifestyle education in adults with overweight or obesity and type 2 diabetes?
Summary
This two-center randomized controlled trial compared 12 weeks of a 5:2 energy-restricted diet, a twice-weekly low-volume HIIT plus resistance-training program, and routine lifestyle education in adults with overweight or obesity and newly diagnosed type 2 diabetes. The diet intervention improved HbA1c more than control, but the exercise intervention did not significantly improve HbA1c versus control. The exercise program did improve body fat mass, fat-to-lean mass ratio, liver fat, diastolic blood pressure, and preservation of lean body mass versus control, with no serious adverse events reported in the exercise or diet groups.
Methodology
- Adults aged 40-70 with overweight or obesity and type 2 diabetes diagnosed within the prior 2 years.
- 326 participants.
- Cycle ergometer HIIT plus machine-based resistance training; home adaptations included treadmill, running in place, and no-equipment strength training.
- Work intervals: Single 4-minute HIIT bout.
- Intensity: HIIT at 85-90% age-predicted HRmax; RT at 80% 1RM.
- 5-minute warm-up + 4-minute HIIT + 5-minute cooldown + resistance training duration not specified.
- 2 days per week, mostly nonconsecutive.
- 12 weeks.
- Two-center, open-label, three-arm, parallel-group randomized controlled trial with 12-week intervention and 36-week postintervention follow-up.
- HbA1c, Glucose metabolism, Body composition, and Liver fat content were tracked.
Outcomes
HbA1c
Diet improved HbA1c significantly more than control, while exercise did not significantly differ from control.
Diet -0.72% vs control -0.37%, between-group -0.34% (95% CI -0.58 to -0.11, p = 0.007); exercise -0.46% vs control -0.37%, between-group -0.09% (95% CI -0.32 to 0.15, p = 0.47).
Body weight and BMI
Diet reduced body weight and BMI more than control; exercise did not significantly reduce body weight or BMI compared with control.
Exercise vs control body weight -0.48 kg (95% CI -1.24 to 0.28, p = 0.21); BMI -0.16 kg/m2 (95% CI -0.44 to 0.11, p = 0.25).
Lean body mass
Exercise better preserved lean body mass than control.
Exercise vs control 1.08 kg (95% CI 0.05 to 2.10, p = 0.039).
Body fat and liver fat
Exercise reduced body fat mass, fat-to-lean mass ratio, and liver fat compared with control.
Exercise vs control body fat mass -1.62 kg (95% CI -2.57 to -0.66, p = 0.001); fat-to-lean mass ratio -4.17 percentage points (95% CI -6.66 to -1.68, p = 0.001); liver fat -1.27 percentage points (95% CI -2.14 to -0.30, p = 0.012).
Blood pressure
Exercise significantly reduced diastolic blood pressure compared with control but not systolic blood pressure.
Exercise vs control diastolic BP -2.48 mmHg (95% CI -4.89 to -0.07, p = 0.043); systolic BP -3.10 mmHg (95% CI -6.92 to 0.72, p = 0.11).
Safety
No serious adverse events occurred in diet or exercise groups, and adverse events were evenly distributed.
One serious adverse event occurred in control group: hospitalization due to nasal polypectomy.
Insights
- For adults with early type 2 diabetes, low-volume HIIT plus resistance training can improve body composition outcomes even when HbA1c does not improve beyond lifestyle education.
- A twice-weekly HIIT dose may need resistance training and clinical monitoring to reproduce this study's outcomes.
- HIIT content for diabetes should distinguish between body composition benefits and glycemic control benefits.
- Consumer translation should include medical-screening cautions for diabetes, glucose monitoring, and medication-management boundaries.
Limitations
- Participants only had type 2 diabetes diagnosed within the prior 2 years and HbA1c 7.0-8.9%
- Excluded insulin-treated and higher-risk patients
- Body composition was measured with bioelectrical impedance rather than DEXA
- Finger-prick glucose monitoring may underestimate hyperglycemic and hypoglycemic episodes
- No data were collected on whether participants maintained the diet or exercise regimen after intervention
- Exercise required supervision and equipment for the standard center-based protocol
Safety
- No serious adverse events occurred in diet or exercise intervention groups.
- One serious event occurred in the control group: hospitalization due to nasal polypectomy.
- Serious adverse events or adverse events were evenly distributed across groups.
- Medication and glucose-monitoring safety rules were used during the intervention.