Gmail API read message

I'm trying to read an email using gmail api. But the format of the body message is unreadable.

static void Main(string[] args)
    {
        UserCredential credential;

        using (var stream =
            new FileStream("client_secret.json", FileMode.Open, FileAccess.Read))
        {
            string credPath = System.Environment.GetFolderPath(
                System.Environment.SpecialFolder.Personal);
            credPath = Path.Combine(credPath, ".credentials/gmail-dotnet-quickstart.json");

            credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(stream).Secrets,
                Scopes,
                "user",
                CancellationToken.None,
                new FileDataStore(credPath, true)).Result;
            Console.WriteLine("Credential file saved to: " + credPath);
        }

        // Create Gmail API service.
        var service = new GmailService(new BaseClientService.Initializer()
        {
            HttpClientInitializer = credential,
            ApplicationName = ApplicationName,
        });


        UsersResource.MessagesResource.ListRequest request = service.Users.Messages.List("me");
        IList<Message> messages = request.Execute().Messages;
        if (messages != null && messages.Count > 0)
        {
            foreach (var messageItem in messages)
            {
                var readMessage = service.Users.Messages.Get("me", messageItem.Id).Execute();
                var body = readMessage.Payload.Parts[0].Body.Data;
            }
        } }

When I debug my test application, the body variable gets the value:

        body    "DQpLaW5kIFJlZ2FyZHMsDQoNCldpbGwNCg0KV2lsbCBLZWx0eQ0KMzIzLjI1Mi44Njk5DQp3a2VsdHlAZ21haWwuY29tIDxtYWlsdG86d2tlbHR5QGdtYWlsLmNvbT4NCmh0dHBzOi8vd3d3LmZhY2Vib29rLmNvbS9iaWdibHVlZG93bnRvd24gPGh0dHBzOi8vd3d3LmZhY2Vib29rLmNvbS9iaWdibHVlZG93bnRvd24-DQp3d3cubWV0cm9saWZlcHJvcGVydGllcy5jb20gPGh0dHA6Ly93d3cubWV0cm9saWZlcHJvcGVydGllcy5jb20vPg0KDQpCZWdpbiBmb3J3YXJkZWQgbWVzc2FnZToNCg0KRnJvbTogIkNSRVhpIiA8bm90aWZpY2F0aW9uc0BjcmV4aS5jb20-DQpTdWJqZWN0OiBJbmR1c3RyaWFsIENSRSBBc3NldHMgRm9yIFNhbGUgfCBHcmVhdCBPaGlvIExvY2F0aW9ucyB8IEVhc3kgQWNjZXNzIHwgTkFJIFNwcmluZw0KRGF0ZTogSnVseSAxNCwgMjAxNyBhdCA5OjAxOjQwIEFNIFBEVA0KVG86IHdrZWx0eUBnbWFpbC5jb20NClJlcGx5LVRvOiBpbmZvQGNyZXhpLmNvbQ0KDQogPGh0dHA6Ly9lbWFpbC1saW5rcy5jcmV4aS5jb20vd2YvY2xpY2s_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_dXBuPVVnWW9yUXo0"  string

Does anyone know why?

Thanks