dietary changes

Last reviewed 04/2018

Most obese patients underestimate their food intake.

A sensible aim is to reduce the current calorie intake by about 600 kcal/day.

  • this goal may be achievable without a significant reduction in the volume of food provided high calorie fatty foods are swapped for carbohydrate
    • breads, pasta, potatoes and rice aid satiety and should provide the bulk of every meal
    • fruit and vegetables - the energy density of most fruits and vegetables is low. They add bulk to a meal and help promote a feeling of fullness. They are rich in vitamins and phytochemicals which may have a protective effect on health
  • fat should provide less than 30% of the dietary calories
    • fat is the most energy dense macronutrient (9kcal/g, compared with approximately 4kcal/g for carbohydrate or protein). Reducing dietary fat will reduce energy intake. People should be given advice on interpreting food labels, preferring those that contain <3g/100g fat and choosing low fat substitutes where possible.Also, to avoid adding fat during cooking and to consume only very small quantities of high fat foods
  • protein is very satiating compared to carbohydrate and fat
    • modest increases in protein intake may help appetite control (which may account for the popularity of the Atkins diet). Liberal quantities of lean protein sources, such as carcase meat, poultry (without skin), low-fat dairy products and pulses can facilitate adherence to a low-fat diet

High fat/high sugar foods such as cakes, biscuits, chocolate and sweets are energy-dense and should be avoided. However, eating these foods occasionally will not ruin weeks or months of dietary restraint (1)

NICE have stated that, with respect to diet in adults with obesity (2):

  • diets that have a 600 kcal/day deficit (that is, they contain 600 kcal less than the person needs to stay the same weight) or that reduce calories by lowering the fat content (low-fat diets), in combination with expert support and intensive follow-up, are recommended for sustainable weight loss
  • low-calorie diets (800-1600 kcal/day) may also be considered, but are less likely to be nutritionally complete
  • do not routinely use very-low-calorie diets (800 kcal/day or less) to manage obesity (defined as BMI over 30)
  • very-low-calorie diets may be used for a maximum of 12 weeks continuously, or intermittently with a low-calorie diet (for example for 2-4 days a week), by people who are obese and have reached a plateau in weight loss
  • any diet of less than 600 kcal/day should be used only under clinical supervision.

Dietary intervention alone is not usually effective in maintaining longterm weight loss.

Dietary treatment should also aim to alter broader aspects of eating behaviour

  • these include:
    • Portion size: reducing energy intake can be achieved by reducing habitual portion sizes (1).
      • the following are appropriate portions:
        • (a) Breakfast Cereals -3 tablespoons,
        • (b) Rice - 2 heaped tablespoons and (c) 2 egg-sized potatoes
    • Meal pattern:
      • structured meals can help individuals to choose less energy-dense foods, rather than succumb to high fat/high sugar foods. (Skipping meals rarely helps to reduce overall energy intake)
    • Snacking: individuals should be given advice on snack choices. Fresh or dried fruit, raw vegetables, diet yoghurts and low-sugar breakfast cereals with skimmed or semi-skimmed milk are appropriate


  1. British Heart Foundation (December 2004). Factfile - the dietary management of obesity.
  2. NICE (November 2014). Obesity guidance.