Intensive lifestyle intervention including high-intensity interval training program improves insulin resistance and fasting plasma glucose in obese patients
Question
Does a 9-month intensive lifestyle program including supervised HIIT, resistance training, and Mediterranean diet counseling improve glycemic control and insulin resistance in obese patients?
Summary
In a retrospective cohort of 72 obese adults who completed a 9-month lifestyle program, supervised HIIT plus resistance training and Mediterranean diet counseling improved fasting glucose, fasting insulin, and HOMA-IR, especially in those who were insulin resistant at baseline. Because there was no control group and non-completers were excluded, the evidence is supportive but not causal.
Methodology
- Seventy-two obese adults who completed a clinical lifestyle program; 54 women and 18 men.
- 72 participants.
- Cycle ergometer HIIT plus resistance circuit and Mediterranean diet counseling.
- Work intervals: 15-30 s.
- Recovery: 15-30 s passive recovery.
- Intensity: 80% maximal aerobic power; target Borg RPE 15.
- 60 min total: 34 min HIIT plus 20 min resistance training.
- 2-3 supervised sessions/week; encouraged 1-2 additional unsupervised moderate sessions/week.
- 9 months.
- Retrospective clinical cohort
- Fasting plasma glucose, Insulin resistance, and HbA1c were tracked.
Outcomes
Fasting glucose
Fasting plasma glucose decreased after the program.
5.5 +/- 0.9 to 5.2 +/- 0.6 mmol/L; p<0.0001
Fasting insulin
Fasting insulin decreased after the program.
98 +/- 57 to 82 +/- 43 pmol/L; p=0.003
HOMA-IR
Insulin resistance improved, especially among participants who were insulin resistant at baseline.
All subjects 3.6 +/- 2.5 to 2.8 +/- 1.6, p=0.0008; insulin-resistant subgroup 5.1 to 3.5
HbA1c
HbA1c did not change significantly.
5.72 to 5.69%; p=0.448
Insights
- A long, supervised lifestyle program combining HIIT, resistance training, and diet counseling can improve fasting glycemic markers in obese adults.
- Benefits were strongest for those with baseline insulin resistance.
- Because diet and exercise were bundled, the HIIT-specific contribution cannot be isolated.
Limitations
- Retrospective design.
- No comparator group.
- Only completers with final data were analyzed, creating selection bias.
- Mediterranean diet adherence data were unavailable.
- HOMA-IR is a surrogate and OGTT was not used.
- Participants paid for and self-selected into a clinical program.
Safety
- Adverse events were not reported.
- Exercise was supervised by kinesiologists in a clinical prevention center.