High intake of cereal fibre has been shown to be associated with reduced weight gain and improved insulin sensitivity. We hypothesize these effects are due to the short chain fatty acids derived from the bacterial fermentation (breakdown) of fibre in the colon (large intestine). Insulin resistant subjects will be randomized to receive 2 servings of a low-fibre cereal (eg. puffed rice) or 2 servings of a high-fibre cereal (wheat bran cereal) per day for one year. The effects of the diets on body weight, appetite, abdominal fat, blood short chain fatty acids, glucose, insulin, lipids and hormones will be measured

Inclusion Criteria:

• Non-diabetic male or non-pregnant females
• aged 18-60
• BMI<36
• fasting insulin >40pmol/L (70%ile)

Exclusion Criteria:

• intention to lose >5kg in weight
• presence of diabetes (fasting glucose >6.9mmol/L)
• use of diuretics, beta-blockers or weight reducing drugs
• use of antibiotics in last 3 months and use of antibiotics more than once annually for the last 2 years
• significant gastrointestinal, liver or kidney disease
• use of lipid-lowering drug
• major medical or surgical event in last 6 mo.
• fibre intake >30g/d
• inability to eat low or high fibre breakfast cereals
• unwilling or unable to give consent or comply with protocol