CHO/Fat ratios for weight loss maintenance

[Guest guest]

Hi all,

Re CHO/Fat ratios for weight loss maintenance, the following is interesting. From examining the details of

“British Medical Journal, Toubro S, Astrup A. Randomised comparison of diets for maintaining obese subjects' weight after major weight loss: ad lib, low fat, high carbohydrate diet v fixed energy intake. BMJ. 1997 Jan 4;314(7073):29-34. PMID: 9001476”

it was interesting to note that fat in normal proportions in the diet is a real detriment go staying on reduced weight diets. This is true irrespective of the method used to lose weight and the time required on different weight loss diets. From their conclusions, "Firstly, energy restriction as a tool for inducing weight loss is highly effective in obese subjects" was of special interest.

Details are described below and seem like a good guide on dieting in general as well, IMHO.

Al not AL

Reduction programmes

The first phase of the study consisted of weight reduction programmes. All the subjects were randomly assigned to either eight weeks of low energy diet (2 MJ/day) (n=21) or to 17 weeks of conventional hypocaloric, high protein diet (5 MJ/day) (n=22). Both diets were supported by an anorectic compound (ephedrine 20 mg and caffeine 200 mg thrice daily,14 Let-igen, Nycomed DAK A/S, Roskilde, Denmark). The duration of the diets was chosen to achieve similar weight losses in both groups. During this phase, the subjects were split into four groups of 7-13 subjects each (two of low energy diet and two of conventional diet).

The low energy diet consisted of nutrition powder (Bli-Let, Nycomed DAK A/S) dissolved in water and was taken as five daily meals (six for men). This met all recommendations for daily intake of high quality protein (women 60 g, men 72 g), essential amino acids, carbohydrate (30.5 g), vegetable fat (6 g), and fibre (17.5 g). The subjects took a daily supplement of a tablet containing vitamins, minerals, and trace elements and a 1 g fish oil capsule containing at least 350 mg essential omega-3 fatty acids to ensure that their daily intake met recommended amounts.15

The conventional diet consisted of ordinary foods and a daily vitamin and mineral tablet (Apovit, Nycomed DAK A/S). The diet plan included recommended amounts of listed food items, together with recipes for low energy marinades and dressings.

The subjects attended the department weekly as outpatients, and the two low energy diet groups were kept apart from the two conventional diet groups. All the groups received nutritional instruction and behaviour therapy: they were instructed by the same staff in dietary guidelines, basic nutritional education, and behaviour therapy sessions of 1-2 hours. Every fortnight the patients were interviewed about adverse effects, and their body weight was measured on a decimal scale (Seca model 707, Copenhagen). Body composition was estimated by the bioimpedance method with an Animeter (HTS-Engineering, Odense, Denmark), and fat free mass and fat mass were calculated with Danish standard equations.

Weight maintenance programmes

After the weight reduction phase the use of low energy diet and anorectic compounds was stopped and subsequently forbidden. The 37 subjects who completed the weight reduction phase were re-randomised to two different one year, non-pharmacological, weight maintenance diet programmes (the low energy diet groups and conventional diet groups being randomised separately). Two groups of patients were assigned to a low fat, high carbohydrate diet consumed ad lib and two groups to a diet of fixed energy intake.

Ad lib, low fat, high carbohydrate diet–The subjects were given a 24 page (A5 format) dietary leaflet specifying details to be included in their daily habits: (a) use a thin layer of butter or margarine on bread or none at all, ( use the frying pan less often and throw the dripping away, © use cooking methods that require less fat, (d) select lean meat and meat products (<10 g fat/100 g of food item), and (e) eat more carbohydrates, especially complex carbohydrates. Alcoholic beverages were allowed only on special occasions. The aim of the diet was to achieve a macronutrient composition that produced 20-25% of energy intake from fat, at least 55% of energy intake from carbohydrate, and the rest from protein.

Fixed energy intake diet–In order to achieve quantitative as well as qualitative self control, the subjects were introduced to an educational system, which consisted of isoenergetic interchangeable units, represented by 144 counters, each with a small picture of the food it symbolises. The counters were also colour coded, with each colour representing a food group: blue counters for foods rich in protein, green counters for foods rich in fibres and low in energy content, and red counters for foods rich in fat and sugar. The energy content of the food represented by each counter was 260 kJ (62.5 kcal). The subjects were encouraged to restrict the number of red counters they used and to use at least seven blue counters a day. At the start of the programme, the subjects had a daily "ration" of 30 counters (7.8 MJ/day), which could be subsequently adjusted: if a subject's weight increased the daily ration of counters was reduced stepwise by two to a minimum of 20. At a ration of 20 counters, subjects were ordered to complete a seven day record of the weight of their food intake. Once a month, the subjects' body weight, body composition, and any side effects were recorded.

During this phase the subjects were allowed, but not encouraged, to loose weight. They were seen in groups two or three times a month for the first six months, and once a month for the following six months. The sessions consisted of dietary instruction, reinforcement, support, and nutritional education and practical instruction in food preparation in the department kitchen.

Conclusion

Several points must be considered when comparing the effectiveness of different diets. Firstly, energy restriction as a tool for inducing weight loss is highly effective in obese subjects, and trials have reported mean weight losses of 10-15 kg over six months of treatment.5 14 16 The relapse rate, however, is remarkably high–50% of all patients regain or exceed their pretreatment weight at 12 months' follow up. Because a high fat content of the diet plays a role for the development of obesity, the low fat principle seems more appropriate as a tool for weight maintenance. We therefore chose to test the two diet principles after an initial weight loss of 12-13 kg.

Secondly, compliance is a crucial factor for weight loss. During their trial of ad lib, low fat diets, Lyon et al gave subjects an evening meal to be consumed at home. The meal was enriched with radiolabelled glucose, and the subjects were asked to collect expired air in a test tube after the meal. The recovery of radiolabelled carbon was used as an index of adherence to the diet, and the authors found a strong correlation between adherence and loss of body fat (r =0.74). Consequently, a small or no weight loss may be attributed to lack of compliance to the diet.

Finally, for nutritional public health policy, our results support the theory that a low fat diet could contribute to preventing obesity. Even a mean weight loss of 2-3 kg may produce a substantial reduction in the prevalence of obesity on a population basis. The recent observation that the prevalence of obesity is increasing concomitantly with a decrease in dietary fat content does not in conflict with this, because the level of daily physical activity is also decreasing. There is an important interaction between exercise level and fat oxidation, indicating that the amount of fat in the diet has to be reduced for a given reduction in total energy expenditure in order to achieve energy balance.