Meal replacement products (MRPs) are usually bars, or powdered drinks that need to be mixed with fluid; usually water or milk. They are mostly high in protein, low to moderate in carbohydrates, low in fat and often have high amounts of various vitamins and minerals (and perhaps herbal extracts as well).
However, there is such a variety these days it is difficult to be so general. For example, a serving of an MRP might have about 300kcal and include about 40g of protein, 20-30g of carbohydrates, and about 5g of each of fat and fibre. In contrast, a serving of a sport meal (not a powder or bar) might be about 400-500kcal and include about 15g of protein, 50g of carbohydrate, 15-20g of fat and 10g of fibre.
Moreover, a typical powdered MRP will be very low in sodium, perhaps less than a hundredth of a gramme, whereas sport meals are often high in sodium, perhaps half a gramme or more. There are also breakfast and bedtime MRPs. The breakfast MRPs are mostly the same as the usual MRPs but with a little less of each ingredient and somewhat cheaper. A bedtime MRP serving might be about 200kcal and include about 40g of protein, and only 2 or 3 grammes of carbohydrates and fibre; they often have little or no vitamins and minerals.RELATED: RECOMMENDED PLANS FOR YOU
The current costs per serving are as follows: about £1 for a usual MRP or a bedtime MRP, about £0.30 for a breakfast MRP, and about £4 for a sport MRP; clearly, they can quickly and easily become an expensive habit. It should be noted that all of the information on MRPs above is extremely vague, and no doubt the ingredients and costs will vary considerably depending on the manufacturer.
The main reason people use MRPs is for fat loss, and this is where most or all of the convincing research for them has come; in trials, MRPs have shown to be very effective supplements for those overweight or obese but that is not to suggest that they are any better than a wholesome diet. Many such trials have included a large number of subjects – 80 or more is not unusual – and many last for three to ten months.
The evidence for fat loss is there, and MRPs have shown to lower fat and LDL cholesterol levels considerably, particularly the high-protein MRPs. That said, a fairly recent trial found that obese subjects who were on a supervised diet-and-exercise programme lost more weight than those encouraged to be more physically active and who were put on an MRP-diet.
Furthermore, the supervised group were better able to maintain their improvements. Incidentally, protein powders are often considered to be MRPs, especially since most of the usual type are high in protein, but in this series on sport supplements protein will be considered separately in a later article.
As for athletes, there seems to be little or no research of their concern, but MRPs are included here since they might be useful from time to time but certainly not for general use; an athlete should treat meal ‘replacements’ as a supplement for a rare occasion, if at all. MRPs have no proven benefits over food, and may have unnecessary amounts of nutrients that make it hard to tailor your intakes. Moreover, they can work out to be a needlessly expensive habit and many find them to be unpalatable with an unpleasant aftertaste.