Thanks @Jacek,

It worked, just pasting the code below for future reference if someone get stuck here.

def make_request(path, params) do
    url = construct_url(path, params)
    headers = [
      {"Accept-Encoding","gzip, deflate"},{"Content-Type", "application/json"}
    ]

    case HTTPoison.get(url, headers) do
      {:ok, %HTTPoison.Response{status_code: 200, headers: resp_headers, body: body}} -> 
      
        resp_headers
          |> check_if_gzipped
          |> unzip_body(body)
          |> decode_body

      {:ok,  %HTTPoison.Response{status_code: status_code }} -> 
          {:error, status_code}
      {:error, error} -> {:error, error}
    end
  end

  def check_if_gzipped(headers) do
    Enum.any?(headers, fn (kv) ->
      case kv do
        {"Content-Encoding", "gzip"} -> true
        {"content-encoding", "gzip"} -> true
        {"Content-Encoding", "x-gzip"} -> true
        _ -> false
      end
    end)
  end

  def decode_body(body) do
    case Poison.decode(body) do
      {:ok, decoded} -> {:ok, decoded}
      {:error, error} ->{:error, error}
    end
  end

  def unzip_body(true, body), do: :zlib.gunzip(body)

  def unzip_body(false, body), do: body

  defp construct_url(path, params) do
    path <> params
  end