Intervention

The intervention was an evidence-based weight management programme. Counterweight-Plus [16, 23] was delivered in the participants’ own general practice by the practice nurse or local dietitian who received 12 h training and ongoing mentoring in the programme from the study research dietitians. Weight loss was initiated by TDR using a low-energy, 3452–3569 kJ/day (825–853 kcal/day) formula diet for 12 weeks, extendable up to 20 weeks to allow for planned breaks and participant wishes, followed by stepped food reintroduction (FR) over 2–8 weeks, and a structured programme with monthly visits to support long-term weight loss maintenance (WLM).

To avoid postural hypotension during weight loss [18, 24, 25], the DiRECT protocol adopted the approach used in the Counterbalance study [18] that all antihypertensive (including diuretic) medications were withdrawn on commencement of TDR, irrespective of baseline BP or number of antihypertensive medications being prescribed. Advice to reduce dietary sodium was reinforced [19]. Multi-purpose medications such as beta-blockers were continued if they had been prescribed for an indication other than hypertension.

Blood pressure was measured (sitting and rested) at each intervention visit (1 week after start of TDR then every 2 weeks until the end of FR and monthly thereafter). A pre-specified protocol (Table ​(Table1)1) based on current national clinical guidelines [7, 22] was applied for medication reintroduction if SBP exceeded 165 mmHg (during weeks 1 or 2 of TDR) or 140 mmHg subsequently. There was no pre-planned testing for postural hypotension by lying/standing BP.

Protocol for reintroduction of antihypertensive medications

1. In first 2 weeks after stopping antihypertensives and diuretics:

If SBP is over 165 mmHg on repeated measurement, restart one drug, as below.

For participants whose glycaemic control deteriorated, anti-diabetes medications were also reintroduced [19]; medications such as GLP-1 agonists that reduce BP were not used. A checklist of possible side effects related to TDR, including dizziness, was completed at each study visit.