The benefits of swapping to wholegrain foods
A common theme of dietary guideline recommendations is to eat more wholegrain foods at the expense of highly refined grains. These recommendations arose from the result of accumulating evidence that has linked wholegrain foods to reduced risks of type 2 diabetes and heart disease.
People who eat the recommended amount of wholegrain foods are less likely to be overweight. The higher nutrient value and fibre content of wholegrains over refined grains can help to control appetite, improve glycaemic (blood glucose) control and insulin sensitivity, and beneficially alter gut microbiota.
Controlled trials where people switch to eating more wholegrain foods do not always show a benefit on body weight. The difficulty in doing such studies comes from how problematic it can be in isolating the effects of wholegrains from eating a healthier overall diet.
A new study has strictly controlled diet quality while keeping body weight constant to see if metabolic effects of wholegrain foods could be detected.
Researchers calculated the specific energy needs of 81 men and women aged between 40 and 65. The first two weeks had everyone eating the same types of food to set a baseline for energy needs to maintain body weight. For the next six weeks, each person was randomly allocated to eat either a wholegrain or refined grain diet.
Two clear benefits were identified in the wholegrain diet. Eating wholegrain foods caused a greater faecal output, meaning less of the potential calories in food were being absorbed and instead were lost through the stool.
The other change was that resting metabolic rate rose in those eating wholegrains. Combining these two favourable energetic effects would mean a deficit of around 420 kilojoules (100 Calories) per day, which is no small number when spread over months and years.
Raising metabolic rate and stool energy excretion, combined with a benefit of fibre on appetite, builds a stronger rationale for recommending a switch to more wholegrain foods in assisting weight loss.
A downside of the work was the short duration of the trial and the use of a very controlled diet which may not translate to free living food choices.
Eating more wholegrains in place of highly refined grains could be an important part of healthy eating and keeping weight in check.
Last Reviewed: 10/01/2020
© Norman Swan Medical Communications.
Karl JP et al. Substituting whole grains for refined grains in 6-week randomized trial favorably affects energy balance parameters in healthy men and post-menopausal women. American Journal of Clinical Nutrition Epub online February 8, 2017. doi. 10.3945/ajcn.116.139683.
6 Foods to beat inflammation
Ongoing inflammation is behind medical conditions such as high blood pressure and insulin resistance. Find out 6 foods that can reduce inflammation, with myDr.com.au.
Diet changes improve depression outlook
The first dietary intervention study of its kind has found dietary changes to be beneficial in helping moderate to severe depression.
The glycaemic index (GI) ranks carbohydrates by how quickly your blood glucose (blood sugar) levels will rise after eating that food.
Vitamin and mineral supplements: when are they needed?
Vitamin and mineral supplements won't convert poor food choices into a healthy diet, but relevant quantities can address deficiencies at certain life stages.
Should we reconsider bread in our diet?
Breads can include various grains and seeds, and there are many things to look out for when choosing bread, such as the flour, GI, salt and additives.