Yogurt is a popular dairy product made by adding live bacteria to milk.
Without added sugar, it is generally considered to be very healthy. Some studies even link yogurt to a reduced risk of weight gain and obesity.
Recently, a team of scientist decided to do a thorough review of all the evidence on yogurt consumption and weight loss/gain.
This article presents a detailed summary of their findings.
Conventional yogurt is a type of fermented milk that contains cultures of bacteria, mainly Streptococcus thermophilus and Lactobacillus delbrueckii.
Probiotic yogurt contains added probiotic bacteria, such as Bifidobacterium lactis and Lactobacillus acidophilus. Yogurt must also contain lactic acid, a minimum of 2.7% milk protein and less than 15% milk fat.
However, until now, no reviews have examined how yogurt affects body weight.
This was a systematic review of studies on the association between conventional yogurt and weight management.
This review and meta-analysis examined the association between conventional yogurt and weight-related outcomes in healthy adults.
It was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines (4).
The researchers found 22 eligible studies, 13 observational studies, 6 randomized controlled trials and 1 controlled trial.
These studies examined the effects of yogurt in healthy, normal populations, but not in people with obesity or specific diseases.
Additionally, the researchers excluded studies investigating probiotic yogurt, kefir, kumis or yogurt with added vitamins, protein or fat.
Bottom Line: This systematic review and meta-analysis examined how eating conventional yogurt affects weight-related outcomes.
Finding 1: Eating Yogurt is Associated With Lower Body Weight
Observational studies show that eating yogurt is associated with lower body weight, body mass index (BMI), body fat and a smaller waist circumference.
However, observational studies cannot prove a cause-and-effect relationship.
It is highly likely that a high consumption of yogurt is associated with other healthy lifestyle factors that could influence body weight.
Bottom Line: Observational studies showed that eating yogurt was linked to lower body weight, BMI, body fat and a smaller waist circumference.
Finding 2: Eating Yogurt Might Reduce Weight
A total of 6 randomized controlled trials (RCTs) were included in this systematic review. Here are brief summaries of 5 of the selected studies.
- Compared to the control, yogurt caused more weight loss, body fat reduction and reduction in waist circumference. It also helped retain lean body mass (5).
- Yogurt did not reduce body fat, compared to the control groups (6).
- Body weight, body mass index (BMI), waist circumference and body fat did not decrease more after consuming yogurt, compared to a placebo (7).
- Eating yogurt did not lead to a greater reduction in body weight, BMI or body fat, compared to a placebo (8).
- Yogurt caused a small, but statistically significant, increase in body weight (9).
However, this last study was not a weight loss trial and the participants were given one liter of several dairy products (9).
Also, it should be noted that only one of these studies showed that yogurt caused significant improvements to body weight and composition (5).
Yet when the results from several of these studies were combined in a meta-analysis, there was evidence that yogurt may have modest weight loss benefits.
Nevertheless, none of these trials could prove that the yogurt itself actually led to changes in body weight.
Bottom Line: Randomized controlled trials have provided mixed results, but together suggest that yogurt may cause modest weight loss.
How Might Yogurt Affect Weight?
The available evidence suggests that yogurt may promote a healthy body weight.
This could be due to a higher protein intake among people who eat a lot of yogurt.
Additionally, some yogurts contain live probiotic bacteria, which may promote weight loss. This is discussed in a previous research review.
However, this review focused on conventional yogurt, not probiotic yogurt.
Bottom Line: Why conventional yogurt would promote weight loss is unclear. However, studies suggest that probiotics may have health benefits.
This systematic review was conducted according to strict standards and guidelines. In itself, it doesn’t appear to have many limitations.
The main limitations apply to the selected studies. Most of them were observational, but a few randomized controlled trials were also included.
These randomized controlled trials had several limitations. Some didn’t provide all relevant methodology, which made comparing and interpreting the results difficult.
Additionally, only one of the trials reported the type of bacterial strains in the yogurt used. For this reason, it can’t be ruled out that some of them included probiotics.
This also applied to the observational studies. The methods used to estimate yogurt consumption, such as food frequency questionnaires, are often inaccurate.
Finally, the authors concluded that none of the studies they used managed to separate the effects of yogurt, proving that yogurt consumption caused weight loss.
Bottom Line: The studies included in this systematic review had several limitations, and none could prove that eating yogurt led to weight loss.
Summary and Real-Life Application
In short, this systematic review indicates that eating conventional yogurt may have modest weight loss benefits.
However, the evidence was limited, and higher-quality studies are needed before a solid conclusion can be reached. Additionally, if you decide to eat more yogurt to lose weight, selecting sugar-free yogurt is recommended.
And although not the focus of this study, studies suggest that probiotic yogurt may have even greater health benefits.