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Does Eating More Protein Help you Lose Weight?

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When planning your weight loss strategies it is important to think about your food choices. Before you think about the minute details of micro nutrients and such, you need to consider the importance of macro nutrients – the food groups needed in bigger amounts that provide you with energy.

As the saying goes ‘don’t major in the minors’.

In this article we’ll let you know all there is to know about protein, and whether it can help you with your weight loss goals.

Read on to find out:

  • What is protein?
  • Can more of it help with weight loss?
  • Are there side effects from too much of it?

What is protein?

Protein (PRO) is classed as a macronutrient or ‘macro’ as it is required in large amounts – it functions to maintain and repair body tissue, regulate hormone and enzyme production, and form antibodies to fight off infections and illnesses. It also provides us with energy too – 4kcal per gram in fact.

Against other macronutrients, it is the most satiating – it keeps you fuller for longer. This means that by adding foods that are rich in this nutrient into your diet you can reduce overall energy intake. We’ll take a look at this in more detail in the research section of this article.

Additionally, this macro has the highest Thermic Effect of Food (TEF) – this is a system that demonstrates how nutrients influence appetite. One study in the journal Physiology & Behavior for example, suggested that the thermic effect of PRO was 20-30% compared to 5-10% for carbohydrate and 0-3% for fat [1].

Basically, 20-30% of the calories you eat from this macronutrient are burned off just to digest it – and this process helps to increase satiety. It’s a win, win situation!

So it appears that this nutrient can help to keep you full, whilst at the same time increasing thermic effect. But does that translate to weight loss? Let’s take a look at what the research says…


Protein-for-Fat-Loss

Key Point: This macronutrient is the most satiating and has the highest thermic effect.


The science: can a high protein diet support weight loss?

#Study 1: Johnston et al [2]

In this study, 10 healthy women were asked to consume a high carbohydrate and a high protein day diet on separate occasions and with a large gap in between.

When energy expenditure was measured after each diet day, the thermic effect was 2.5 times higher than in the carbohydrate one, suggesting an increased energy cost associated. The authors concluded that high-PRO, low-fat diets and may help explain the efficacy of such diets for weight loss. 

#Study 2: Weigle et al [3]

It’s not only a thermic effect that is beneficial for weight loss. Studies also show that this nutrient can reduce appetite and therefore allow you eat less calories.

Weigle et al investigated how increasing protein would effect body weight, satiety and hormonal balance. 19 volunteers were asked to eat a diet of 50% carbohydrates across the study period, but for short intervals, changed levels of the macronutrient from low – 15%, to high 30%.

The results of the study showed that satiety was much higher in the high PRO diet, with energy intake decreasing by an astounding mean average of 441kcal. Additionally, fat mass reduced by 3.7kg and body weight by 4.9kg. This all occurred over a 16 week period.

This demonstrated that this macronutrient can have positive effects on appetite as well as metabolism.

#Study 3: Due et al [4]

This study aimed to look at the longer-term effects of a fat-reduced, high-PRO diet over 6 month period and review at 12 months.

A total of 50 overweight and obese volunteers were put on a strict diet for a 6 month period that was made up of either a high protein component (25% total energy) or medium (12%). Fat remained fairly low in both groups (30%).

Upon completion of the diet, the higher protein group had lost 9.4kg in weight in comparison to the medium group with 5.9kg. On top of that, they had a 10% greater reduction in abdominal fat levels too after 12 months.

These results were echoed in the next study too.

#Study 4: Halkjaer et al [5]

In one of the biggest cohort studies in this area, 22,570 women and 20,126 men were examined over a 5 year period to investigate the influence of diet on abdominal fat levels.

They analysed the effects of different diets and total energy intakes on development of abdominal fat levels. They found that protein intake was inversely related to weight loss and differences in waist circumferences.


Eat-Protein-to-Lose-Weight

Key Point: Research show that not only can protein boost metabolism, it can reduce appetite, help you lose weight and increase fullness too.


Are there side effects to too much protein?

There is a major focus on allowing PRO to take up a large relative proportion of energy in the research studies discussed above. But are there any potential side effects to this type of diet?

Previously it has been suggested that excess intakes of the macronutrient may be bad for the kidneys due too excess amounts of nitrogen excretion [6]. However, evidence was lacking and since the publication of such studies, research has emerged showing that high intakes do not alter kidney intake.

In one study by Poortmans [7] for example, it was concluded that there is no published evidence that a high-PRO diet produces negative effects on kidney and liver metabolism.

Another side effect often associated with high-PRO diets is that of increased calcium excretion leading to reduced bone health and density. To assess this, Darling et al [8] conducted a meta-analysis to find out – this is an analysis of all existing data.

The results found that the effect of protein on bone density was if anything positive with 1-2% increases, and with no significant negative effects identified.

As an energy-providing nutrient, you need to be aware that it could still put you into a calorie surplus if consumed in excess, and this can contribute to weight gain. It is advised that whilst aiming for a high intake, you monitor overall energy intake closely.


Summary – Can protein help you lose weight?

Protein is a macronutrient used for a variety of functions such as growth and repair of tissue, as well as hormone and enzyme regulation.

This nutrient has the highest satiety value, meaning that out of all macronutrient it will keep you fuller for longer. It also has the highest thermic effect – it takes a over a quarter of food energy intake to digest it.

Research shows that by increasing intake levels of this nutrient you can lose weight – it works in two different ways. The first is that it increases your metabolism, and the second is that it creates fullness which reduces overall appetite. It has been shown to not only help you reduce weight, but specifically reduce fat from your belly.

There are no real side effects to high-PRO diets, other than potential for weight gain if you don’t keep an eye on overall energy intake. Previous reports about links to kidney issues or accelerated bone loss are unfounded and have little to no published evidenced to substantiate them.


References

  1. van Baak, MA. Meal-induced activation of the sympathetic nervous system and its cardiovascular and thermogenic effects in man. Physiol Behav 2008; 94: 178-86.
  2. Johnston, CS et al. Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy, young women. J Am Coll Nutr. 2002; 21(1): 55-61.
  3. Weigle, DS et al. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations Am J Clin Nutr. 200582(1): 41-48
  4. Due, A et al. Effect of normal-fat diets, either medium or high in protein, on body weight in overweight subjects: a randomised 1-year trial. Int J Obes Relat Metab Disord. 2004; 28(10): 1283-90.
  5. Halkjaer, J et al. Intake of macronutrients as predictors of 5-y changes in waist circumference. Am J Clin Nutr. 2006; 84(4): 789-97
  6. Lemon, PW. Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle? Nutr Rev. 1996; 54(4 Pt 2): S169-75.
  7. Poortmans, JR et al. Do regular high protein diets have potential health risks on kidney function in athletes?. Int J Sport Nutr Exerc Metab
  8. Darling, AL et al. Dietary protein and bone health: a systematic review and meta-analysis. Am J Clin Nutr. 2009; 90(6): 1674-92