The GDA Diet By Nigel Denby
The GDA Diet by Nigel Denby

Can using guideline daily amounts (GDA) help you get slim? Dietitian Juliette Kellow BSc RD takes a look at The GDA Diet by Nigel Denby

The GDA Diet By Nigel Denby

Reviewed by Dietitian, Juliette Kellow BSc RD

What’s the Theory?

Guideline Daily Amounts, known as GDAs, exist for calories and nutrients including sugars, fat, saturates and salt and outline the maximum amount we should eat each day. More than 20,000 food products now show the number of calories and grams of sugars, fat, saturates and salt in a portion of the food on the front of their packaging, together with information on the percentage they each contribute to the total daily allowance. This provides vital information to help us lose weight and enables us to compare one product with another to find one that’s suits our needs.

What Does the Diet Involve?

The diet focuses on a 20: 30: 30: 20 rule. This sounds complicated, but simply means splitting GDAs into meals and snacks as follows:

• breakfasts should provide 20% of the GDA
• lunches should provide 30% of the GDA
• evening meals should provide 30% of the GDA
• snacks should provide 20% of the GDA (preferably as two snacks, one mid-morning and one mid-afternoon, with each providing around 10% of the GDA).

If you have more than 13kg or 2 stone to lose, you will shift those excess pounds on 2,000 calories a day. Conveniently, this matches the adult GDA for calorie. So you simply use the information shown on the front of food packaging to follow the 20: 30: 30: 20 rule. However, if you have less than 13kg or 2 stone to lose, you only need 1,700 calories each day to lose weight. This means the percentages are not suitable to use (as they’re based on a higher daily calorie allowance). As a result, you need to use the actual calorie values given on the front of packaging.

Fortunately, the book provides an easy breakdown for both the 2,000 and 1,700 calorie plans, showing the actual calorie, sugar, fat, saturates and salt values you should have each day, together with the percentages you should be aiming for at each meal and snack. For each calorie allowance, there are 7-day plans for busy people, vegetarians and budget eating.

What Can I Eat in a Typical Day?

Example from the 1,700-calorie plan on a budget

Breakfast: 125ml orange juice and 2 slices wholemeal toast and 2tsp each of reduced-fat spread and jam.

Morning Snack: Large handful of grapes with 4 water biscuits with 30g reduced-fat cream cheese.

Lunch: 100g canned mackerel with 100g pasta (dry weight) and a large bowl of mixed salad with 1tbsp fat-free dressing. Plus 125g pot low-fat yogurt.

Afternoon snack: 2 crumpets with 2tsp jam.

Dinner: 1 individual margherita pizza with 80g vegetables as extra toppings and a large bowl of salad with 1tbsp fat-free dressing.

How Much Weight will I Lose?

By including 30-40 minutes of activity every day, you can expect to lose 1-2lb a week.

What Else Does the Book Include?

There’s useful information on how to break out of the diet cycle. You’ll find helpful advice on calculating your Body Mass Index and waist circumference. Plus there’s good information on the main GDA nutrients and how to eat fewer of them, together with brief sections on goal setting, eating out, shopping and cooking tips, and typical portion sizes.

Recipes are included for some of the days, there’s a chapter on exercise and some useful Q and As.

Juliette’s Verdict

The author is a registered dietitian so as you would expect, the theory is based on the holy grail of weight loss – quite simply, if you want to shift those pounds, you need to take in fewer calories than you use up. Using GDAs as a way to lose weight, also guides you towards keeping tabs on those components of your diet – namely sugar, fat, saturates and salt – you should also be aiming to eat less of for good health. So top marks for its sensible approach to weight loss.

On the downside, if you don’t ‘get’ percentages, struggle with maths or don’t own a calculator, chances are you’ll struggle. Whilst the meal plans themselves are simple, the accompanying GDA charts – which are crammed with numbers and percentages – will probably scare the life out of you.

Added to this, not all products are labelled with GDAs. Sainsbury’s, Asda and Waitrose own-brand products, for example, label the front of their products with traffic light colours rather than GDA’s. Similarly, GDAs have been developed predominantly for pre-packaged foods such as ready meals, sauces and pizzas so if you do a lot of cooking from fresh, natural ingredients, you’ll struggle to find GDA information.

The Food Standards Agency is currently reviewing advice for manufacturers regarding nutrition labelling on the front of food packaging so in the next couple of years, there might be changes.

Finally, the two diet plans offer only a modest calorie restriction and so you may find weight loss is very slow (below 1lb a week), especially if you’re not doing a lot of exercise or have just half a stone to lose.

This may lead to frustration and a lack of motivation, with the result that you go looking for a plan that will speed up your weight loss.

Bottom line, this book is best suited to people who are good with figures, know their way around a calculator and tend to rely heavily on processed and ready-made foods.

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