Comparison of Different Weight Loss Diets With Different Protein Content
Comparison of Different Weight Loss Diets With Different Protein Content
High-protein diets better preserve lean mass than conventional low-fat diets. However, they
 are costly and have potential health risks. Preserving lean mass is important for sustaining
 high resting energy expenditure, leading to greater initial weight loss, better weight
 maintenance and improving blood sugar levels. Branched-chain amino acids (BCAA) supplements
 are known to preserve lean mass but their effects during weight loss have not been examined.
 Investigators want to investigate if a BCAA-supplemented diet is more effective than a
 standard hypocaloric diet in terms of the aforementioned benefits, and yet has less
 detrimental effects than a high-protein diet for weight loss. Using a 16-week weight loss and
 8-week weight maintenance intervention, overweight and obese men and women will be randomized
 to either a hypocaloric diet with BCAA or placebo supplements or a high-protein diet with
 placebo supplements. Participants' compliance to the diet versus supplements will be
 compared. Body composition, resting and diet-induced energy expenditure, insulin sensitivity
 will be measured and blood samples taken before and after weight loss. These findings will
 inform on the benefits of BCAA-supplementation during energy restriction and may offer an
 alternative cost-effective strategy for weight loss and maintenance, without the adverse
 health effects of a high-protein load.
The prevalence of obesity globally and in Singapore continues to rise despite increased
 public awareness and efforts to control weight. Its association with chronic metabolic
 diseases, including diabetes, hypertension, cardiovascular diseases, signify the serious
 implications of obesity on public health. There remains, however, no scientific consensus on
 the optimal methods for weight loss and its maintenance over longer periods of time. The
 Atkins diet was introduced in the late 1990s and has since fuelled the popularity of using
 high-protein diets for weight loss. Scientific evidence have since shown high-protein diets
 to be more effective than conventional low-fat, high-carbohydrate diets in producing greater
 weight loss, at least in the short-term. More importantly, high-protein diets also reduce the
 amount of lean tissue lost during weight loss and may help to maintain weight loss to a
 greater extent than conventional diets. However, high-protein diets are also known to raise
 esterol, albeit improving TG and HDL-cholesterol levels. This could be due to the higher
 amounts of saturated fats that accompany foods rich in animal protein. In addition,
 high-protein diets may lower bone mineral density and impact on kidney function. High-protein
 diets are also more expensive than conventional low-fat, high carbohydrate foods , which is
 an important consideration for longer term compliance.

 Supplements containing branched-chain amino acids (BCAA:leucine, isoleucine and valine) are
 commonly used among muscle builders and athletic community. BCAAs have been shown to
 stimulate protein synthesis and preserve lean mass. While a few studies have examined BCAA
 supplementation with low protein diets for weight loss and found depletion of other essential
 amino acids, the effects of BCAA supplementation with moderate-protein hypocaloric diets on
 lean mass preservation during weight loss in energy-restricted obese patients has, to our
 knowledge, not been investigated. Compared to consuming a high (animal) protein diet, which
 is also rich in BCAAs, taking BCAA supplements would be a much more convenient and affordable
 way to obtain similar if not greater quantities of BCAA, without the adverse health effects
 of a high-protein load on the body.

 In this study investigators primarily aim to investigate in overweight/obese subjects,
 whether a BCAA-supplemented (moderate-protein) hypocaloric diet (BCAA) when compared to a
 standard (moderate-protein) hypocaloric diet (CT) will result in greater lean mass
 preservation, resting and diet-induced energy expenditure, and improved insulin sensitivity.
 Investigators will also examine the effects on lean mass preservation and insulin sensitivity
 changes between BCAA-supplemented diet and high-protein hypocaloric diet (HP). As a secondary
 aim, investigators have also powered the study to examine if the BCAA-supplemented diet has
 added advantage to the high-protein diet by incurring less negative effects on bone mineral
 density and renal function.

 In addition, investigators will determine the participant's compliance to the diet versus
 supplements as a weight loss and maintenance strategy. The findings of this study will
 provide us novel insight on BCAA-supplementation in the hypocaloric diet. If this study is
 successful, BCAA-supplementation on a hypocaloric diet could provide an alternative to a
 standard (moderate-protein) hypocaloric diet for weight reduction strategy without the
 attending potential health risks of a high protein load e.g. reduced bone mineral density and
 detrimental effects on renal function.

 There are three main hypotheses which investigators propose to examine.

 Hypothesis 1: A BCAA-supplemented hypocaloric diet (BCAA) would lead to greater lean mass
 preservation during weight loss compared to a standard (moderate-protein) hypocaloric diet
 (CT).

 Diets with varying diet composition, including low-fat, high-carbohydrate diets to
 high-protein, low-carbohydrate diets have been tested in search of the optimal macronutrient
 composition for weight loss. High-protein diets have been highly favored for their ability to
 initiate greater initial weight loss. However, accumulative data from recent studies has
 shown no significant differences in amount of weight loss between high-protein diets and
 other traditional (normally low-fat, high-carbohydrate) energy-restricted diets in the longer
 term (16 weeks to 1 year). It appears that total energy intake, rather than diet composition,
 is the most important determinant of longer term weight loss.

 However, an overriding advantage of high-protein diets is their favorable effects on body
 composition, that is preserving greater lean mass, compared to high-carbohydrate diets,
 during weight loss in adult obese patients, independent of energy intake. A recent
 meta-analysis demonstrated that high protein diets (protein > 1.05g/kg body weight) are
 associated with up to 1.21 kg additional fat-free mass retention compared with diets of lower
 protein intake. Lean mass or fat-free mass is a main determinant of basal (resting) energy
 expenditure. Its greater preservation would reduce the weight loss-induced decreased in
 energy expenditure, which might have two important implications. Firstly, higher basal energy
 expenditure during weight loss could lead to greater weight loss for the same amount of
 calories consumed. Secondly, the amount of lean mass preserved at the end of weight loss
 might mitigate weight regain during maintenance phase of weight loss, i.e. success of weight
 maintenance.

 Branched-chain amino acids like leucine, isoleucine and valine are substrates for protein
 synthesis and also potent nutrients that regulate protein metabolism. Supplementation with
 leucine or leucine-rich protein sources have been suggested to develop muscle mass or prevent
 protein loss in conditions characterized by muscle protein wasting. In human studies, the use
 of leucine or leucine-rich protein sources supplementation have been well-investigated to
 optimize the effects of exercise on body composition.Several studies have examined the impact
 of chronic (average of 3 months) leucine-rich amino acid supplementation in healthy elderly
 humans, and have demonstrated significant improvement in lean body mass, muscle strength and
 physical capacity.

 Whether the lean mass preservation during high-protein hypocaloric diet is due to the
 presence of the higher amounts of BCAA content is less clear. Two studies have examined the
 use of whey protein (rich in BCAA) in weight loss but it was uncertain if the benefits of
 enhanced weight loss with less lean muscle loss can be attributed to the BCAA alone or due to
 the enrichment of other nutrients like calcium and bioactive peptides in the whey protein
 fraction. It is also not clear whether animal sources of protein (rich in BCAAs) are more
 beneficial than plant sources of protein on energy expenditure, body composition , satiety
 and fat loss.

 To investigators' knowledge, no studies have specifically examined the beneficial effect of
 BCAA supplementation with a moderate-protein diet on lean mass preservation during weight
 loss in energy-restricted obese patients. Investigators hypothesize that similar to a
 high-protein diet (as shown in literature), a BCAA-supplemented hypocaloric diet would also
 lead to greater lean mass preservation than a standard (moderate-protein) hypocaloric diet
 during weight loss. In addition, investigators want to examine the effects on lean mass
 preservation between BCAA-supplemented hypocaloric diet and high protein hypocaloric diet.

 Hypothesis 2: Improvement in insulin sensitivity with a BCAA-supplemented hypocaloric diet
 (BCAA) is greater than a standard (moderate-protein) hypocaloric diet (CT).

 The insulin stimulating effects of proteins maybe mediated through specific amino acids,
 making them potent modulators of insulin action and glucose metabolism. In animal models,
 BCAA supplementation has been found to improve glucose tolerance and stimulate glucose uptake
 in skeletal muscle by mechanisms involving glycogen synthase activity. While energy
 restriction and weight loss have positive effects on insulin sensitivity , whether diet
 composition further impacts on insulin sensitivity is still inconclusive. Several studies
 found significant improvement in insulin sensitivity after high-protein diets compared to
 control diets, independent of weight loss, while others did not. As skeletal muscle mass is a
 major determinate of insulin sensitivity, investigators postulate that due to greater lean
 mass preservation, the BCAA diet would result in greater improvement in insulin sensitivity
 compared to CT diet.

 Hypothesis 3: The BCAA-supplementation diet (BCAA) would be easier to adhere to and has less
 detrimental effects on bone mineral density and renal function than the high-protein diet
 (HP), leading to better (short-term) weight maintenance and less weight regain.

 Maintaining weight loss is a greater challenge than the weight loss process and may not be as
 easily achieved. Studies have shown that weight regain is significantly lesser in subjects in
 the high-protein group compared to control group after six months to a year on a
 weight-maintenance diet. In these studies, study foods are provided and may not reflect
 real-life free-living situations during weight maintenance phase. Achieving a high-protein
 diet long term can be costly and requires careful planning of meals. To what extent subjects
 can continue to maintain the same diet composition as their weight loss diet on their own
 accord at energy balance during weight maintenance has not been well-investigated The
 effectiveness of longer term BCAA supplementation in hypocaloric diet has also not been fully
 investigated. If BCAA supplementation could induce similar metabolic improvement as of a
 high-protein diet during the weight loss phase, it might help to maintain body weight through
 easy administration and greater compliance in the longer term.

 In this study, investigators proposed to provide BCAA supplements to the BCAA group and
 placebo supplements provided to the HP and CT groups throughout the entire study (weight loss
 and maintenance phases).

 Study foods will, however, only be provided during the weight loss phase. Investigators
 speculate that overall, adherence to supplementation would be better than adherence to the
 respective diet compositions at the end of the weight maintenance phase for subjects in all
 three groups. Investigators hypothesize that while subjects on the HP and BCAA diets will
 have less weight regain in the initial weight maintenance phase (due to greater lean mass)
 than the CT group, the BCAA group will have the least weight regain at the end of weight
 maintenance phase due to better compliance.

 Concerns have been raised over the safety of high-protein diets. Studies have indicated that
 increase protein intake is associated with increased renal calcium excretion, negative
 calcium balance, bone resorption and causes hyperfiltration. At the same time, it is also
 known that loss of bone mass often accompanies weight loss induced by calorie restriction.
 Whether high-protein diets have a detrimental impact on bone mineral density and renal
 function is still inconclusive. In this study, investigators hypothesize that the
 BCAA-supplemented diet would result in lesser detrimental effects on bone mineral density and
 renal function than the high-protein diet.

 Other secondary hypotheses:

 The three dietary interventions may lead to significant differences in markers of
 cardiometabolic outcomes including inflammatory markers

 The resting/basal metabolic rate change with time, and diet induced thermogenesis, may differ
 between the three groups

 The resting basal metabolic rate change in the subjects with weight loss at 16 weeks predicts
 the weight gain/rebound at 24 weeks.
Inclusion Criteria:

 1. Be willing and able to comply with study procedures and given written informed consent

 2. Chinese, aged 21-45 years old

 3. Body mass index (BMI) between 25 -35 kg/m2 and % body fat of more than 25 %.

 4. Sedentary adults, with <1 episode of exercise per week

 5. Not have a history of food allergies or food intolerances

 6. Have maintained a stable body weight for at least 3 months prior to the study.

 7. Be a non-smoker

 8. Drinks less than 3 caffeinated beverages per day (coffee/tea/energy drinks)

 9. Drinks less than 3 units of alcohol per day

 Exclusion Criteria:

 1. Subjects with diabetes, renal impairment, high blood pressure, gastrointestinal
 problems, asthma, eczema, anaemia or on medications that will affect glucose
 metabolism (e.g. corticosteroids) or lipid metabolism/insulin resistance (e.g. niacin,
 fibrates, metformin) and other significant medical conditions, which in the
 investigator's opinion would confound interpretation of results.

 2. Recent changes (gain or loss) in weight of >5% over the past 3 months

 3. Significant changes in diet over the past 3 months

 4. Any use of weight-reduction drugs in the past 6 months

 5. Use of any prescription medication that cannot be safely discontinued within 14 days
 prior to study entry

 6. Have special dietary needs/restrictions e.g. vegetarian diet or unable to consume
 fish, seafood and beef

 7. History of eating disorders or irregular eating habits

 8. High level of physical activity (exercise > 5hr per week)

 9. Women who are pregnant and lactating and women of reproductive age group who plan to
 conceive within 6 months. A pregnancy test will be performed for women in the
 reproductive age group.

 10. Have contraindications to Magnetic Resonance Imaging (MRI) that includes metallic
 implants, pacemakers or stimulators, or any other methodology applied in the study.

 11. Have been involved in any clinical or food study within the preceding month.

 12. Presently consuming amino acid or protein-related supplements.