Our study showed that intensive weight loss achieved by use of a low-energy formula diet was accompanied by significant increases in vitamin D and B12
levels. This is striking, as nearly half of our participants had a deficiency of vitamin D at baseline and about one in five showed deficiency in vitamin B12
. At week 16, the percentage of participants being deficient in vitamin D and B12
had decreased significantly. The correction of these vitamin deficiencies may very likely have been due to the formula products given, as the product was enriched in both vitamin D and B12
. However, some of the vitamins responsible for the improvements, that is, vitamin D may have been liberated from fat tissue during the weight loss.13
The participants lost about 10% of their weight during this short period of 16 weeks and as this weight loss was mainly due to fat loss from fat stores, it could have been a source of vitamin D, far larger than that given in the supplement.14
The increase in vitamin D was paralleled by a decrease in PTH (Pearson's correlation coefficient r
<0.01). One may speculate if this was influencing the unchanged BMC and even increased BMD during the program, a most interesting finding. Measurement of BMD by DXA is the most widely used surrogate marker of the bone status. However, using BMD to determine a response to therapy may take 1–2 years.15
From other weight loss studies, changes in BMC and BMD has though been seen already after 3 months.16
Our results are in disagreement with earlier studies with other weight loss programs, which led to decreased BMC and BMD and accelerated bone turnover.16, 17, 18, 19
In a calorie restriction study by Redman et al.
, (2008) the participants were offered diets providing the recommended daily intake of all essential vitamins and minerals, and the participants did not experience any negative effect on bone status with weight loss.20
This supports that by making sure that the diet applied includes all essential nutrients (like vitamin D and calcium) it is possible to minimize or prevent loss from the muscle and bone. The formula diet program provided at least 100% of the daily-recommended intake of calcium and vitamin D for adults between 18 and 65 years of age at the time the study was conducted. The Danish guidelines recommended a daily intake of vitamin D of 5
μg and of calcium 800
mg. It has previously been shown that diets high in calcium or dairy products can suppress bone resorption.21, 22
As calcium absorption is dependent on the presence of 1.25 (OH)2
vitamin D, the requirement of calcium can only be meaningfully discussed if the vitamin D status is sufficient. The optimal vitamin D intake is not known and there is evidence suggesting that the present recommended intake is actually inadequate and needs to be increased.23
However, based on our data we can conclude that the intake of both vitamin D and calcium was sufficient to cause an increase in BMD and to prevent loss of BMC. With their weight loss, >60% of the participants experienced clinically significant improvements in pain and disability.11
This could also have caused an increase in physical activity and, if this was the case, increased physical activity could explain the relatively low loss of LBM as well as low loss of bone observed in our participants. The participants were though not advised to change their physical activity pattern during the study, but were advised to stick to their usual routines.
Measurements of BMC and BMD by dual energy X-ray absorptiometry are known to be affected, although to a minor degree, by layer of excessive fat.24
There are also differences between dual energy X-ray absorptiometry scanners used. In general, Hologic scanner measurements show an increase in BMD whereas Lunar scanner measurements show a decrease in BMD with weight loss.24
In our study, we used a Lunar scanner (GE Medical systems). Despite of this we found an increase in BMD with weight loss. We therefore must conclude that this observation is real and if anything the increase in BMD is measured as too low.
In this study we measured the blood levels of the micronutrients, we expected to be of clinical importance in relation to our study population. However, it would have been interesting to measure changes in a wider panel of micronutrients in connection to this type of weight loss program, as it is well known that obesity is often accompanied by a low status.
Obesity may be associated with nutrient deficiencies and the average overweight subject may suffer from a nutritionally inadequate diet. When trying to lose weight by consuming less food, individuals may unwittingly reduce essential nutrient intake even further. This creates an important role for nutrient-dense foods like formula diets, which allow adequate intake of macro- and micronutrients although still providing smaller amounts of energy. Given the growing rate of obesity, it is important for subjects deciding to reduce their energy intake to maintain a nutritionally sound diet, providing adequate vitamins, minerals and macronutrients.
Our data suggest that weight loss can be achieved effectively and safely with low-energy formula products, as long as this diet contains a sufficient amount of nutrients. This is supported by the Look Ahead Study, where the number of meal replacements consumed in the first 6 months was significantly related to weight loss at week 26 (r
<0.001), as was the total number consumed for the year to weight loss at week 52 (r
As our obese patients need support to keep to a healthy diet, the formula diet may take the burden of having to deliberately choose the low-fat healthy option at each meal time, and replacement of one or two meals a day with the low-calorie formula diet may be the ‘medicine', which helps the patients to keep their micronutrients at acceptable levels as well as the obtained weight loss on a more permanent scale.