Can cooking oil cause weight loss?
Bupa investigative news - 16 June 2003
written by Rachel Newcombe, reporter for Bupa's Health Information Team
Excess weight and high cholesterol are key concerns, especially with their links to serious diseases such as heart disease. According to the latest research, blended functional oil could help reduce cholesterol, increase metabolism and aid weight loss in men. So, is there any truth in the research? Could oil really have fat-busting abilities and what's the best way to lower cholesterol?
KEY POINTS
According to the British Nutrition Foundation, a "functional food" is "any food that contains an ingredient that gives the food health-promoting properties over and above its usual nutritional value". Examples include cholesterol-reducing spreads or fortified bread.
Researchers in Canada developed a blended functional oil. Tests on volunteers appeared to find that the oil could increase metabolism, lower cholesterol and, in some cases, aid weight loss.
Experts are interested in the findings and agree that the blend could help lower cholesterol. However, they say hardly any weight was lost and oil alone is unlikely to be beneficial for helping people lose weight.
Existing oils, such as monounsaturated and polyunsaturated oils can help lower cholesterol. A better way of losing weight is to be more active and eat healthily.
What were the headlines?
The world media jumped on the research, swiftly reporting it in a variety of guises. One of the main reporting angles was the weight loss side, with many reports suggesting it could be the latest miracle cure and fat fighting aid, especially for men. Others focused on the way it can help reduce cholesterol and the potential benefits for healthy eating.
Examples of headlines include, "Cooking oil 'fights fat'", "Cooking oil 'could fight flab'", "Cooking oil that helps dieters to fight fat while frying", "New cooking oil reduces cholesterol", "Cooking oil burns off weight", "Cooking oil hailed as 'fat buster'", and "Oil blend 'lowers cholesterol and helps men lose weight'".
What is the bigger picture?
The research was carried out at McGill School of Dietetics and Human Nutrition in Montreal, Canada and led by Professor Peter Jones. The team conducted two clinical trials to look at the effects of a functional oil, created by the biopharmaceutical company Forbes Medi-Tech, on a group of men and women who were all 25 pounds overweight. The research has been published in four research journals: the International Journal of Obesity, the Journal of Nutrition, Obesity Research and Metabolism.
The functional oil contained medium chain triglycerides (MCT) - whereas most oils have long chain triglyceride fats (LCT) - and consisted of 67 per cent tropical oils, 13 per cent olive oil, 6 per cent coconut oil and 5 per cent flaxseed oil. Each trial lasted for 27 days, with a "washout" period of four weeks between each one.
The participants were given a typical North American style diet, including breakfasts such as French toast with maple syrup and yogurt, and an evening meal of spaghetti, salad and baguette, followed by a date square. At the beginning and end of each trial the participants underwent MRI (magnetic resonance imaging) scans. This enabled the team to produce 40 cross-sectional images of the participants' bodies and showed where the fat was located in their bodies.
They discovered the functional oil managed to reduce the cholesterol of both sexes by up to 13 per cent. Olive oil, which has previously been regarded as the best cholesterol fighter, only reduces levels by 4.5 per cent. The body scans also showed people consuming functional oil decreased their total body volume and upper body fat.
Men lost an average of one pound of weight per month on this diet. But women didn't lose any weight, despite the fact that they experienced higher metabolic rates.
Describing how the oil is burned rather than absorbed by the body, Professor Jones said, "It is directed towards the liver for combustion and burned as energy. The oil is not stored in the body as fat and heightens the metabolism, which is a key in maintaining a healthy body weight. There is also some provocative data suggesting that oils rich in MCT reduce appetite."
More research is now being carried out, but they hope the oil could be produced as a functional health product and be sold to consumers.
"People should have realistic expectations about this new functional food. It does appear to have desirable effects on blood lipids as do some butter-replacement spreads on the market, but Professor Jones and his group have not shown it to make a useful contribution to weight loss. We should all try to eat healthily and exercise as part of everyday life to gain and maintain an appropriate weight."
Dr Virginia Warren
assistant medical director
Bupa Group
What does this mean?
Amanda Wynne, spokesperson for the British Dietetic Association (BDA), said, "This is a small study of short duration. The results are interesting, but much more research on larger numbers of people for a longer duration would be necessary before any firm conclusions could be made. This should not be seen as a magical solution to weight loss or an excuse to eat a high fat diet and take little exercise."
The fact that cholesterol was lowered by the oil blend didn't surprise her, as "the oil contains phytosterols," which aid cholesterol reduction. It worked because the "MCTs are more rapidly digested and absorbed and are transported to the liver".
The weight loss aspect, however, wasn't so convincing. "The men only lost 1lb in weight over the 27 days," said Amanda. "The ideal rate of weight loss is 1-2lbs per week so this isn't a very significant loss of weight. It could just be a coincidence that the men lost a little weight and the women didn't."
A spokesperson for the Food Standards Agency said "Polyunsaturated and, to some extent, monounsaturated, oils are known to lower blood cholesterol levels and help reduce the risk of diseases such as heart disease." However, they warned that blended oil alone is unlikely to help aid weight loss and people are advised to use as little unsaturated oil as possible to maintain a healthy lifestyle.
Dr. Sarah Brewer, a GP from Kings Lynn, said, "Our understanding of the role of fats in nutrition is starting to turn on its head. Interesting research involving the Atkins diet, conjugated linoleic acid and now this functional oil are showing that we still don't understand how the body really works."
According to Professor Ian Johnson, head of gastrointestinal health and function research at the Institute for Food Research (IFR), "Some functional foods undoubtedly have a beneficial biomedical function in addition to their nutritional value. A classic example would be high wheat-bran cereals with a proven laxative effect. There are undoubtedly other foods that also act as functional foods; the problem for the industry is to be able to substantiate potential claims. This highlights the need for proper scientific study."
He added that, "IFR is contributing to Passclaim, a five-year EU project focused on determining the scientific criteria for manufacturers to use in the validation of functional foods."
ACTION POINTS
If cooking with oil, choose monounsaturated types such as olive or rapeseed oil, or polyunsaturated oils such as sunflower, soya bean or corn oil. Alternatively, use a spray option.
Choose functional products carefully and look at the labels to see whether they're likely to be of use to you.
As part of a healthy lifestyle, oil should be used in moderation. If you're keen to lose weight and lower cholesterol, try and be more active and eat a healthy, balanced diet.
What does this mean to me?
"The most important aspect to losing weight is to consume less calories than you expend. Simply changing the fat in the diet to functional fat and eating a high fat diet (40 per cent energy) in combination with little exercise would be unlikely to promote weight loss," warned Amanda.
According to Professor Jones, it's best to regard the oil as part of a weight management programme, something to complement healthy eating and exercise, rather than as a diet aid. Likewise, Amanda holds a similar view, and said, "Some functional foods may play a role in health, however they should not be considered a substitute for a healthy balanced diet and an active lifestyle."
The Consumers' Association has raised concerns in the past regarding the claims made by functional foods as, on closer examination, not all are as beneficial for health as manufacturers lead people to believe. They say some cholesterol-lowering products are best suited for people with high cholesterol or who are at risk of heart disease and suggest a careful look at the labels before purchasing.
If you want to improve your cooking habits, Amanda recommends trying spray oils, as they're "great as you use very little of them". Alternatively, "when choosing oils go for the monounsaturated types, such as olive oil or rapeseed oil, or polyunsaturated types such as sunflower oil," she advised.
Summary
The functional oil research is interesting and provides another tangent to the functional foods debate. However, as it's only been trialled on small numbers of people, far more research is needed to fully determine its benefits and effects on health.
Links for more information
- Bupa dietary fat article
- Diet and nutrition section
- Exercise section
- British Dietetic Association
- Food Standards Agency
- British Nutrition Foundation
- Consumers' Association
