Can whey help you lose weight?

In 2021, the Ligue contre l'obésité estimated that 47% of French people were overweight. This rising figure is prompting many people to look for ways to lose weight without affecting their health. Others want to reduce their body fat to improve their body composition or performance.

The sports nutrition market is full of dietary supplements, including whey, a milk protein widely used in bodybuilding to build mass. Yet its image remains controversial. Some claim it helps you lose weight, others that it makes you put on weight.

This article looks at the link between whey and weight loss, to explain why whey can be a healthy aid to weight loss if taken under the right conditions. Even though whey is also used for muscle growth.

That's enough to transform your eating habits and help you achieve your weight loss goals over time.

Whey: can it help you lose weight?

Energy balance: a matter of calories

First, we need to understand a biological mechanism that affects our weight. It's called the caloric balance: a person gains weight when they absorb more calories than they expend.

Conversely, it will lose weight if its caloric intake does not cover its energy expenditure.

To maintain your figure, you need to find the right balance. Without a balanced diet combined with regular physical exercise, you risk theyo-yo effect, leading to rapid weight regain.

That's why focusing on your lifestyle and diet is so important if you want lasting results. As part of these good habits, is whey a slimming milk protein?

Protein powder and weight loss

Like other high-protein products, whey can lead to weight loss, but not directly.

Protein is becoming increasingly important in slimming diets. However, a diet too rich in protein can be harmful to the consumer's health.

In fact, studies tend to prove that obesity in wealthy countries is linked to a diet rich in meat, and therefore indirectly in protein. This is partly because, without physical activity, the body also uses these macronutrients to build up fat reserves.

Whey, like other high-protein slimming products, only helps you lose weight if taken in conjunction with workouts tailored to your target.

It is always used as a complement to a balanced and varied diet to support weight loss, or fat loss for muscle leaning. Its effect on weight loss is indirect.

4 reasons to add whey to your diet

There are many reasons to consume whey and here are the 3 main ones, which concern weight loss.

1 - Whey makes you feel fuller

Protein-rich dietary supplements have the advantage of providing a feeling of satiety, thus reducing the sensation of hunger¹. Their appetite-suppressant effect helps to control appetite and avoid snacking between meals, while keeping calorie intake under control.

In fact, proteins release fewer calories than lipids and as many as carbohydrates. 1 g of protein or carbohydrate corresponds to 4 kcal, while the same amount of fat produces more than twice as much energy.

Macronutrient	Calories per gram	Energy detail
Protein	4 kcal / g	1 g protein = 17 kJ
Carbohydrates	4 kcal / g	1 g carbohydrate = 17 kJ
Lipids	9 kcal / g	1 g fat = 38 kJ
Alcohol (ethanol)	7 kcal / g	1 g alcohol = 29 kJ

This appetite-suppressant effect is due to whey's high leucine content. This amino acid stimulates satiety hormones (GLP-1, PYY) and slows gastric emptying, prolonging the feeling of satiety after ingestion. Around 25-30 g of isolate covers the threshold of 2-3 g of leucine per intake, so there's no need to "overdose".

2 - Higher postprandial energy expenditure

Whey has a high thermogenic effect: around 20-30% of the calories it provides are spent on its own digestion, compared with just 5% for carbohydrates.

This process, known as the thermal effect of proteins, slightly increases the resting metabolism and total energy expenditure.

In other words, consuming a whey shaker temporarily stimulates calorie burning, without requiring any extra effort.

This benefit, though modest, supports a natural caloric deficit and facilitates fat loss when combined with a balanced diet and regular training.

3 - Better body composition

What's more, whey protein is useful for muscle building in sport, thanks in particular to the 9 essential amino acids it naturally provides.

This powdered dietary supplement improves the quality of calorie intake. It is therefore useful for people who want to optimize their body composition, as it reduces the ratio of fat mass to lean mass. Even if the athlete doesn't lose weight, his or her body will be more sculpted, since muscles will develop to the detriment of fat.

4 - Proteins against muscle wasting

For sportsmen and women, and in particular body-builders, whey protein helps build muscle in the post-workout phase.

However, in the context of a diet, if the daily calorie intake is not sufficient to meet energy requirements, the body may consume muscle fibers to produce energy.

Whey, or other protein sources, then "spare" the muscle and prevent muscle wasting in a calorie-restricted situation.

Which whey to choose for weight loss?

Whey isolate, clear whey, gainer... not all protein powders are suitable for a balanced diet, so it's important to choose your whey carefully.

For example, we avoid the consumption of gainer-type whey, which provides a significant amount of carbohydrates and could therefore ruin all efforts made in a weight-loss diet.

That's why, when choosing your whey, it's important to consider the calories it provides. Ideally, a whey suited to your weight loss goals should provide between 350 and 400 kcal per 100 g.

In this case, isolate-type whey protein is the most suitable protein powder, since it's high in purity and low in calories.

By consuming sweetened protein powder, the chances of failing your weight-loss diet increase. This substance habituates the brain to a sweet taste and makes it want to seek out more and more of it in the diet, which is a paradoxical effect in the quest for weight loss.

What about plant sources?

Whey offers :

• a complete amino acid profile,
• rapid absorption,
• high leucine content.

Compared to plant sources alone, it often achieves a better DIAAS score and provokes a moderate insulin response, promoting satiety.

However, in a hypocaloric context, the effective difference also depends on total protein intake, digestive tolerance, cost per gram assimilated...

Whey may be the most "effective", but not necessarily the best for everyone.

Criteria	Whey	Animal proteins (egg, fish, lean meat)	Vegetable proteins (peas, rice, soy, mix)
Protein score (DIAAS)	Very high	High	Variable, often lower
Fast absorption	Fast	Average	Slow/moderate
Effect on satiety	Positive (via leucine, rapid absorption)	Good	Varies according to fiber / antinutrients
Cost per gram assimilated	Moderate to high	Often higher	According to brand / extraction
Digestive tolerance	Good if isolated and without additives	Variable	Sometimes inconvenienced (fiber, antinutrients)

Can I take whey to lose weight without exercising?

Yes, technically, it is possible to take whey to lose weight, without exercising, as it helps to reduce the sensation of hunger, which can be useful for controlling cravings and overall calorie intake. 

However, whey does not replace meals, but rather complements them. A successful slimming diet relies on a balanced diet and regular exercise to consume more calories than you take in. 

It is also possible to consume proteins other than sports supplements, such as lean meats, dairy products, eggs, legumes and certain vegetables and cereals. Protein from the diet should remain the basis of protein intake.

How do I take my whey to lose weight?

When to use whey for weight loss?

The ideal time to consume whey depends on the goal you're aiming for. If you're looking to build muscle mass, it's best to take your protein powder after training.

To accelerate and optimize weight loss, eat it as a dessert or snack to take advantage of its appetite-suppressant effect.

Whey is not a meal replacement, despite its remarkable nutritional qualities. Once again, whey should bepart of a balanceddiet, as part of physical training or a slimming program.

It's also essential to stay well hydrated when dieting, and to be monitored by a professional dietician-nutritionist.

How much whey per day to lose weight?

The daily amount of whey you need to lose weight depends on the rest of your diet. In terms of total protein, you shouldn't exceed 2 g/kg per day, but the exact amount depends on your needs.

You can calculate your caloric needs on our free tool :

In most diets, with an intelligent diet, one whey shaker a day (25g of protein) is enough to meet protein needs and limit muscle loss.

If the aim is solely to speed up recovery, a post-training shaker is sufficient. In this case, whey will tend to be consumed on training days.

It's also important to review your diet as a whole before starting supplementation, to avoid whey shakes constituting an excess that will encourage weight gain in fat mass.

How much protein should a woman eat to lose weight?

ANSES recommends an intake of 0.83 g/kg/d for a non-sporting profile.

However, for weight loss and muscle preservation, this amount can be increased. Research indicates that an intake of 1.3 to 2 grams of protein per kilo of body weight may be more effective for weight loss and muscle preservation.

For example, an active, athletic woman weighing 60 kg could aim for around 100 grams of protein a day.

ANSES confirms that "based on current knowledge, protein intakes of between 0.83 and 2.2 g/kg/d (i.e. 10 to 27% of energy intake) can be considered satisfactory for an adult under 60".

How do you take your protein to lose weight?

First and foremost, protein intake should be spread throughout the day, so that it is consumed at every meal and snack to improve muscle protein synthesis, promote satiety and reduce cravings.

The body is unable to assimilate more than 30 g of rapidly-absorbed protein in a single post-exercise intake. If you need to consume more, it's best to multiply your intake, at least 2 hours apart. 

The quality of protein consumed is just as important as the quantity. It is therefore recommended to opt for complete protein sources that supply essential amino acids, as is the case with meat, fish, eggs, dairy products and certain plant proteins.

Conclusion

There's nothing magical about whey alone. It is effective and useful for weight loss only if incorporated into a balanced diet and adapted physical activity, depending on the athlete's objective. Properly consumed, it becomes an aid to weight loss, as it will reduce cravings, preserve muscle mass and improve body composition.

If the aim is to lose weight sustainably, it's best to choose a pure quality whey, low in sugars and with no additives. It is then consumed as a complement to a balanced and controlled hypocaloric diet. Whey is not a meal replacement: so, to achieve visible results and avoid the yo-yo effect, it's important to distribute your protein intake evenly, between protein-rich foods and supplements, throughout the day.

Whey can help you lose weight, but is no substitute for a balanced lifestyle and regular physical activity.