In today’s study the researchers tackle obesity in a new way. The intention was to try a focused fat loss program on study participants and look at the effects on body composition, lean mass (muscle, more or less) and blood fats, blood sugar, insulin and a fullness hormone called leptin. These were measured before the program, directly afterwards, after 4 days, 4 weeks and then after 1 year. To assess body composition and regional fat and lean mass distribution, two methods (bio- impedance and DXA) were used.

Whey vs Sugar

The researchers recruited 15 fairly healthy men with a BMI over 25 (overweight) and a waist circumference >102 cm to be divided in one of two groups; both following very low calorie diets for four days, one group only ingesting sugar (sucrose) and the other one ingesting only whey- protein (0.8g/kg body weight). Both groups getting about 320kcal/ day. During the intervention they exercised; walked and performed an upper body movement for 8h and 45 min, respectively, a day with the focus of getting to a 5000kcal/ day energy deficiency. 

Effects on Blood Fats

  • Blood sugar, insulin, bad blood fat levels (total cholesterol, LDL, triglycerides, free fatty acids) all fell during the intervention. HDL cholesterol rose. Four weeks later, all but LDL cholesterol were back to normal levels. HDL-cholesterol is commonly known as the “good cholesterol” and LDL cholesterol is commonly known as the “bad cholesterol”, meaning that there was some lasting “good effects” of this diet even after 4 weeks. Reality is not that simple but if you are overweight and do not exercise regularly chances are high that you have high LDL and low HDL, a bad ratio. If you have heart disease, it is good to lower your LDL and increase your HDL cholesterol. For heart healthy people the subject is controversial.
  • Cortisol levels rose during and directly after intervention but returned to baseline after four weeks. Cortisol is a hormone that is commonly increased during time of physical or psychological stress. The increase and then a return to baseline is to be expected.
  • Leptin concentration was lowered during the first four weeks but returned to baseline values within one year. Leptin is a hormone that is secreted from fat (adipose tissue), the more adipose tissue the more leptin is synthesized. In healthy individuals an increase in adipose tissue results in increased leptin levels which in turn results in increased feelings of fullness after a meal (less hunger): part of the body’s way of helping you to lose the added weight. In some overweight people, the signals that leptin is supposed to give does not work anymore, the individuals have become leptin- resistant.

Effects on Fats and Muscle Mass

  • Whole body fat mass was reduced by 2.1, 2.8, 3.8 and 1.9 kg, respectively, following the phases presented above. Four weeks after the intervention the participants were still losing weight: minus 1.7kg compared to directly after. This reduction did not continue but the participants were able to keep off about 2kg in the one year follow up. After the intervention they did not have any guidance and did eat and exercise after their own preferences. The fat loss was mainly from the trunk (belly fat), the same fat that has been shown to have the most negative health impacts.
  • Loss of lean mass was fairly low. The greatest loss was seen directly afterwards (probably due to loss of water) but at the one- year follow up the loss of lean mass was 0.4kg. This is because if you have a lot of fat, your body will prioritize burning fat when you are getting too few calories.
  • Waist circumference was reduced during all phases. Waist circumference is a fairly good marker of overall health. A circumference above 80 for women and 94 for men is associated with increased risk of cardiovascular disease.

Whey Didn’t Help to Save Muscle Mass at 0.8 g / kg

Quite interestingly, the group ingesting whey-protein did not show any extra sparing effect on lean body mass or changes in body composition in comparison to the sucrose group. They both had similar results overall. Protein has been shown to “protect” lean mass when being on a diet but the extreme kcal deficiency and the low protein intake (0.8g/kg body weight) might explain why this didn’t happen in the present study.

Take Home

On this short 4-day intervention, the participants were able to lose about 0.5 kg fat mass/ day (mostly from the trunk/ belly), better their blood fat profile and lower their leptin levels. It didn’t matter if they ate 100% carbs or 100% protein.

If overweight, it might be a good idea to kick start a diet with a similar approach (really low on kcal and high on exercise for a short period) and then keep the following period more controlled than these participants did to really get the most of the intervention.

If you are leaner though, we don’t recommend this though you’ll probably lose a lot of muscle mass. In that case it’s better to go slow and controlled with high protein ingestion when cutting to preserve muscle mass.

NOTE: This approach isn’t for everyone and may have certain health risks if done by the wrong person. Consult with your doctor before attempting this diet as you need to have the proper reserve capacity and not have any prior medical conditions which could be worsened by extreme dieting.


Sources:
doi: 10.1111/sms.12194
Article by team EBT member @jonasliefke, 4th year Medical Student, BSc Physiotherapy. www.jonasliefke.com

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