05 January 2012

Food diaries are the way to go for weight loss

If you're trying to lose weight, it might be time to keep a notebook and pen handy. Dieters who keep food records lose twice as much weight as dieters who don't, research shows.


If you're trying to lose weight, it might be time to keep a notebook and pen handy.

Recent research shows that dieters who kept food records or food diaries lost twice as much weight as dieters who didn't record their food intake.

According to Time magazine, a multi-centre study in the USA found that, compared to other methods of weight loss, keeping a food diary helped slimmers to lose an average of 8kg in a 6-month period, whereas dieters who didn't keep diaries only lost 4kg.

Successful weight-loss tool

The above-mentioned study involved more than 1700 overweight and obese Americans over the age of 25 years. All the test subjects were encouraged to reduce their energy intake, attend weekly group sessions and do moderate exercise for 6 months.

Some participants were also instructed to keep food diaries to record how much food they ate every day. “Hands down, the most successful weight-loss method was keeping a record of what you eat,” said senior researcher Victor Stevens (Gupta, 2008).

Gupta, the author of the Time article, points out that it doesn't help to just write down what you eat, but that it's also necessary to identify eating habits that are contributing to weight gain or an inability to lose weight.

Do you know how much you eat?

Many scientific studies have indicated that most people don't realise:

  • What they're eating
  • How much they're eating
  • Which foods are contributing the most to conditions such as obesity

In view of the above, it's not surprising that many researchers have found that test subjects in general, and obese individuals in particular, go in for so-called “selective reporting”.

Over/under-reporting of food intake
It's a common phenomenon that people who are being interviewed to determine what and how much they're eating, will tend to over-report intakes of foods they regard as “good” and under-report intakes of foods they regard as “bad”.

Obese patients are known for their tendency to under-report how much fat and sugar they eat on a daily basis. Basically, they tend to tell researchers what they think the researchers want to hear.

Guilt also plays an important role in under- and over-reporting of food intake. Most people don't want to admit that they eat too much or "pig out" on unhealthy food.

No idea of quantities

In addition to the above-mentioned problems with reporting on food intake, most individuals don't have an accurate concept of quantities. People just don’t know how much they're eating. This is one of the reasons why various organisations such as Weight Watchers and Weigh-Less place so much emphasis on portion sizes. An important aspect of these weight-loss methods is to teach people what portion sizes they should go for if they want to lose weight.

A good South African example is how most of us regard meat portions. A standard portion of meat is 30g, which contains about 7g of protein, and the Recommended Daily Allowance (RDA) for protein is 50g for adult women and 60g for adult men. So, an adult woman would need to eat about 210g of meat to obtain the 50g of protein a day that she needs to maintain protein balance. An adult man would need to eat 270g of meat a day to satisfy his protein needs.

This of course supposes that the man or woman doesn’t eat any other protein foods (e.g. milk, cheese, yoghurt, eggs, fish, legumes etc). However, most South Africans who can afford it, will happily tuck into 500g of meat at one sitting and still have servings of all the other protein-rich foods listed above.

It is, therefore, fair to say that most people don't know what quantities or portions of food they should eat to either maintain or to lose weight.

Oblivious to everyday items

Researchers will tell you that test subjects will remember to list foods that they eat at main meals, but blithely forget to mention items such as milk and sugar in tea and coffee, snacks eaten between meals, sugar added to cereals, butter added to vegetables, etc. This isn't necessarily part of under-reporting, but being genuinely oblivious to everyday items that we start to take for granted.

Studies that use interview techniques to determine food intake employ trained interviewers and checklists to make sure that all these hidden food items are accounted for in the daily food intake. Slimmers would do well to be reminded of these “invisible” foods and drinks that also contribute to energy intake.

Food diaries can help

This is the reason why it's an excellent idea to keep a food diary and to write down what foods you are eating, what beverages you are drinking and how much you eat or drink at each meal and in between meals in the form of snacks or drinks.

Buy a standard diary to note down your food and drink intake and be honest with yourself. I guarantee this will be a great eye-opener. You will be amazed to see how much you eat and drink. It will also be a revelation to discover trends such as eating too much in general, or too much of certain food or drink categories (fat, sugar, alcohol, sweetened cold drinks, etc).

Gupta reports that he really became aware of his food intake once he started to write down what he was eating. This in turn led to an interest in how much energy he was consuming and by working out his kcal intake he found that he could identify “where those extra calories are coming from”.

Take note of exercise

Gupta suggests that it's also a good discipline to note how much exercise you're doing to keep you on track. He emphasises that keeping a food and exercise diary imposes discipline which will not only encourage you to stick to your resolutions to eat less and exercise more, but that it encourages accountability.

The latter is an important component in taking responsibility for your own health and weight. Only if you have achieved accountability, will you take charge of your slimming successes and failures.

(Dr I.V. van Heerden, DietDoc, updated April 2011)

(Gupta S (2008). Dear (Food) Diary. Time, 13 October 2008, p.44)

Any questions? Ask DietDoc

Read more:

Weight loss: the ultimate guide

Planning healthy snacks
Quiz: How kilojoule savvy are you?


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