Little evidence of benefits for T2DM weight loss programmes
Commercial weight loss programmes
Few studies evaluated the effect of the programmes on blood sugar and the six that did failed to show substantial reductions with any commercial weight loss programme
Johns Hopkins scientists who indirectly investigated the blood sugar effects of ten (out of 32 selected) commercial weight loss programmes have noted a few show promise of benefit for diabetic patients, but far more rigorous research is needed before doctors can wholeheartedly recommend them.
“A few of these programmes may be a viable option for improving blood sugar control in patients with type 2 diabetes and those at risk for the disease,” says study leader, Dr Zoobia Chaudhry, assistant professor of medicine at the Johns Hopkins University School of Medicine. “But we need more gold-standard studies to make that claim.”
Chaudhry said a wealth of previous research has shown that losing even a small amount of body weight — between 5 and 10 percent — can significantly lower blood sugar long term in people with type 2 diabetes. But this research has mostly been based, she said, on intensive lifestyle interventions, including highly controlled diets and coached exercise, which aren’t widely available to the nation’s estimated 29.1 million people with type 2 diabetes.
In contrast, she added, commercial weight loss programmes, such as Weight Watchers, Jenny Craig and Nutrisystem (leading market share programmes), are easy to access – although at a price – across the US and in many other countries.
Though several studies have evaluated how much weight patients tend to lose through these programmes, little was known about how they stack up in terms of glycaemic benefits – their positive effects on blood sugar concentrations. A high concentration is a hallmark of diabetes and can negatively affect long-term health, leading to a host of consequences, including blindness, kidney failure, nerve damage and cardiovascular disease.
To find out more, Chaudhry and her colleagues searched the medical literature for studies that carefully evaluated the effects of various commercial weight loss programmes on blood sugar in overweight and obese individuals, including those with or without type 2 diabetes. They included only randomised clinical trials – the gold standard for clinical research – that lasted at least 12 weeks.
Their search, ‘A systematic review of commercial weight loss programmes’ effect on glycemic outcomes among overweight and obese adults with and without type 2 diabetes mellitus’, which is reported in Obesity Reviews Journal, turned up only 18 studies that met their criteria, few of which focused specifically on individuals with diagnosed and documented type 2 diabetes. A total of ten commercial weight loss programmes were cited in the studies. Among the 764 people across all studies with type 2 diabetes, the Jenny Craig programme reduced hemoglobin A1c – a three-month average of blood sugar concentrations – more than weight loss counselling alone at 12 months, and Nutrisystem and Optifast reduced haemoglobin A1c more than counselling alone at six months.
In 2,428 people without type 2 diabetes, few studies evaluated the effect of the programmes on blood sugar. The six that did failed to show substantial reductions with any commercial weight loss programme.
Chaudhry points out that it’s possible that other commercial weight loss programmes also have positive effects on blood sugar, both for people with type 2 diabetes and others at risk for this disease. However, she said, too few studies have rigorously evaluated glycaemic effects for doctors to recommend commercial weight loss programmes as a whole or any specific program to patients. Chaudhry hopes to investigate this further to uncover more definitive answers for patients and their doctors.